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(DXLLESSONS 

HYGIENIC  PHYSIOLOGY 


WALTER  MOORE  COLEMAN 


LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


BIOLOGY 

LIBRARY 

G 


LESSONS   IN 
HYGIENIC   PHYSIOLOGY 


COLEMAN'S  PHYSIOLOGICAL  SERIES 

A   HEALTH  PRIMER 

An  aid  to  pupils  at  this  difficult  stage  of  school  work  when  they  pass 
from  mere  reading  books  to  the  study  of  text-books.  It  is  based  chiefly 
on  hygiene  and  contains  little  anatomy. 

"  The  matter  is  presented  in  so  simple  a  way  and  is  so  skilfully  inferwoven  with 
the  facts  of  everyday  life  that  we  do  not  see  how  the  pupils  could  help  being  charmed 
with  the  book.  The  chief  object  of  the  volume  is  to  encourage  love  of  health  and 
strength,  simple  living,  and  respect  for  the  sacredness  of  natural  instincts."  —  Pri- 
mary School,  New  York. 

PHYSIOLOGY  FOR  BEGINNERS 

In  the  Physiology  for  Beginners  the  science  is  presented  in  its 
simplest  logical  form.  There  is  an  appendix  containing  the  rudiments 
of  the  biological  sciences  along  the  line  of  Nature  Study. 

"  It  is  interesting  and  practical,  and  is,  with  only  very  ordinary  teaching,  certain 
to  make  pupils  delighted  with  the  study.  The  book  has  the  best  qualities  of  all  the 
best  books  on  physiology  for  children,  and  he  has  combined  them  with  original  ideas 
of  his  own  which  show  that  he  is  master  of  his  subject  and  the  best  method  of  teach- 
ing it."  —  School  Journal,  New  York. 

LESSONS  IN  HYGIENIC  PHYSIOLOGY 

The  book  aims  to  teach  the  science  and  art  of  preserving  health. 
The  teaching  is  based  largely  on  observational  study  of  the  body,  ex- 
periments, and  the  study  of  the  accompanying  charts  and  figures. 

"  Lessons  in  Hygienic  Physiology  differs  from  the  usual  school  physiologies 
in  endeavoring  to  teach,  not  so  much  how  the  body  is  put  together,  as  how  it  works, 
or  rather  how  to  keep  it  working  normally  ;  that  is,  it  undertakes  to  teach  the  art  of 
preserving  health.  ...  A  feature  which  will  especially  commend  the  book  is  the  ab- 
sence of  misleading  statements  in  regard  to  the  effects  of  alcohol,  so  general  in  works 
of  this  character." —  The  Churchman,  New  York. 

"This  book  is  a  model  of  workmanship  in  every  feature — text,  type,  divisions, 
arrangement,  and  illustration  ;  in  mechanical  execution  the  book  is  practically 
perfect,  as  a  work  of  this  nature  is  when  issuing  from  this  publishing  house."  — 
The  State,  Columbia,  S.C. 

THE  ELEMENTS   OF  PHYSIOLOGY 

The  Elements  of  Physiology  has  been  prepared  for  an  extended 
course  in  graded  schools  and  rural  schools,  and  for  a  review  course  in 
high  schools,  academies,  and  normal  schools. 

"  This  book  is  a  marked  advantage  over  most  of  the  school  physiologies  in  that 
the  functions  of  the  cells  and  tissues  are  first  taken  up,  the  book  opening  with  a  study 
of  these  and  leading  up  to  the  complete  and  organized  body.  It  is  also  exceptional 
in  that  it  places  greater  emphasis  upon  hygiene  and  its  application.  It  could  but 
prove  a  valuable  manual  for  study  by  every  person  interested  in  the  consideration 
of  health."  —  Health  Culture,  New  York  City. 

"  We  can  heartily  commend  this  volume.  It  is  clean,  practical,  scientific,  and 
lucid  in  its  style  and  teaching.  .  .  .  While  this  book  is  intended  primarily  for  the 
use  of  students  in  the  public  schools,  there  is  much  in  it  to  interest  the  physician."  - 
The  Alkaloidal  Clinic,  Chicago,  111. 


LESSONS  IN 


HYGIENIC    PHYSIOLOGY 


BY 

WALTER   MOORE   COLEMAN,  A.B. 

i  / 

FELLOW   OF  THE   PHYSICAL   SOCIETY   OF   LONDON  ;    AUTHOR  OF 
LESSONS    IN    SCIENCE   FOR  1 
;A   HEALTH   PRIMER,"   ETC. 


NEW  EDITION  REVISED  AND  ENLARGED 


OF  THC 

UNIVERSITY 

Of 
[UFOR1 


gorft 
THE    MACMILLAN   COMPANY 

LONDON  :    MACMILLAN  &  CO.,  LTD. 
1909 

All  rightt  reurved 


JIOLOGY 

GENERAL  "T" 


COLEMAN'S   PHYSIOLOGIES. 


A   HEALTH   PRIMER.     For  Elementary  Grades. 

PHYSIOLOGY  FOR  BEGINNERS.  For  Intermediate 
Grades.  Fully  illustrated. 

LESSONS  IN  HYGIENIC  PHYSIOLOGY,     ix  +  270 

pages.    Brief,  but  clear  and  comprehensive.     198  illus- 
trations, 1 6  colored.     Thirteen  full-page  plates. 

ELEMENTS  OF  PHYSIOLOGY,  xii  +  374  pages. 
A  very  full  course  in  Physiology  and  Hygiene.  Pro- 
fusely illustrated  in  black  and  colors. 


These  books  are  so  graded  that  in  whatever  school 
years  the  subject  may  be  taught,  a  two-book  or  a  three- 
book  course  may  be  selected  exactly  graded  for  the 
work. 


COPYRIGHT,  1905  AND  1908, 
BY  THE  MACMILLAN   COMPANY. 


Set  up  and  electrotyped.  Published  May,  1905.  Reprinted 
July,  December,  1905;  February,  August,  1906;  October,  1907. 

New  edition,  revised  and  enlarged,  January,  1908.  Reprinted 
January,  1909. 


TO  THE   TEACHER 

For  convenience  in  examining  this  book,  it  may  be  well  to  insert 
a  few  page  references,  as  the  book  is,  in  some  respects,  radically 
different  from  the  usual  school  physiology.  The  book  aims  to 
teach  the  science  and  art  of  preserving  health ;  the  teaching  is 
based  largely  on  observational  studies  of  the  body,  experiments, 
and  study  of  the  charts  and  figures  which  it  contains.  Obser- 
vational study  is  carried  out  by  frequent  single  questions  and 
by  more  lengthy  exercises  (pp.  35,  86,  107,  etc.).  The  experi- 
ments illustrate  some  point  in  physiology  (pp.  14,  21,  25,  etc.); 
they  are  not  merely  copied  from  texts  on  physics  and  chemistry, 
as  is  usual  in  those  physiologies  which  are  not  wanting  alto- 
gether in  experimental  work.  To  aid  in  founding  the  study 
upon  facts  and  not  mere  words,  the  author  has  devoted  a  great 
deal  of  time  to  the  illustrations.  Books  of  this  size  usually 
have  sixty  or  seventy  figures ;  this  book  contains  about  three 
times  as  many,  or  one  hundred  and  ninety-eight  in  all,  sixteen 
of  which  are  colored.  Care  has  been  observed  to  make  use  of 
only  the  best  sources,  and  many  figures  are  drawings  of  speci- 
mens hardened  by  the  new  formalin  method  (Figs.  21,  62,  68, 
133,  etc.).  The  author  has  made  use  of  color  (Plates  IX  to 
XIII),  for  it  has  long  seemed  strange  to  him  that  in  the  geog- 
raphies Maine  is  purple,  Vermont  red,  and  New  Hampshire 
blue  (when  they  are  really  none  of  these,  but  are  green,  brown, 
and  white  by  turns),  yet  expense  must  be  spared  in  the  physi- 
ologies, and  no  hint  given  of  the  natural  tints  of  the  bodily 
organs.  When  physiology  comes  into  its  rights,  the  same  care 
will  be  used  in  teaching  the  human  body  as  in  teaching  the 
political  divisions  of  Africa  and  Australia.  There  is  a  saying 
among  teachers  that  there  is  no  impression  without  expression. 
For  testing  the  accuracy  of  what  has  been  learned,  review 
questions  are  abundant.  However,  mere  reproduction  of  facts 

21903*1 


vi  TO   THE   TEACHER 

learned  is  the  crudest  form  of  expression.  The  best  test  as  to 
whether  a  pupil  has  mastered  a  subject  is  not  the  ability  to  tell 
something  about  it,  but  the  ability  to  do  something  with  it,  to 
make  use  of  it.  For  using  the  knowledge  acquired,  provision 
is  made  in  two  series  of  exercises,  containing  in  all  about  four 
hundred  questions.  The  questions  of  the  first  series  (Thought 
Questions,  pp.  13,  15,  24,  etc.)  furnish  exercise  in  reasoning 
from  different  points  of  view  upon  the  anatomy  and  physiology 
already  learned  ;  those  of  the  second  series  (Practical  Ques- 
tions, pp.  51,  69,  etc.)  test  the  ability  of  the  pupil  to  apply  to 
particular  cases  the  laws  of  hygiene  stated  in  the  text.  The 
exercises  in  composition  writing  are  designed  to  give  scope  to 
the  pupil's  originality. 

To  the  teacher  who  is  using  this  book  a  few  statements  may 
prove  suggestive.  In  the  first  place  it  should  be  understood 
that  criticisms  will  be  highly  appreciated.  Any  suggestions 
from  fellow-teachers  for  making  the  book  more  practical  and 
serviceable  will  be  carefully  considered  by  the  author.  When 
we  remember  that  natural  science  has  been  taught  to  youths 
for  only  fifty  years,  while  mathematics  and  language  have  been 
taught  for  centuries,  it  is  not  strange  that  methods  in  science 
teaching  are  still  in  a  rudimentary  stage.  This  book  is  an 
humble  effort  to  hasten  the  time  when  natural  science  shall  be 
taught  with  the  same  thoroughness  and  thoughtfulness  as  lan- 
guage and  mathematics.  We  would  smile  at  a  grammar  or  an 
arithmetic  which  had  every  exercise  worked  out,  every  conclu- 
sion stated,  every  problem  explained,  and  which  left  nothing  for 
the  pupil  to  do  but  to  absorb  the  statements  given.  Yet  this 
is  exactly  the  plan  upon  which  physiologies  are  written.  The 
school  text-books  written  by  physicians  and  filled  with  technical 
facts,  the  flood  of  hastily  prepared  temperance  books,  and  the 
recent  diluted  physiologies  which  make  the  science  easy  by  omit- 
ting most  of  it,  all  agree  in  one  thing,  —  the  pupil  must  be  given 
no  chance  to  think.  It  is  suggested  that  a  whole  lesson  be  de- 
voted to  each  of  the  longer  exercises,  just  as  a  set  of  examples 
in  arithmetic  constitutes  a  whole  lesson.  By  thinking  out  every 
one  of  the  four  hundred  problems,  the  pupil  will  form  the  habit 
of  reasoning. 


CONTENTS 

CHAPTER  I 

PACK 

INTRODUCTION    ..........       x 

CHAPTER  II 
THE  SKIN  ...........      l6 

CHAPTER  III 
THE  SKELETON  .......       «       •       •      3*> 


CHAPTER  IV 
THE  MUSCLES    .......       •       •       •      S3 

CHAPTER  V 
THE  CIRCULATION      ......       •       •       •     79 

CHAPTER  VI 
THE  RESPIRATION      .........    I02 

CHAPTER  VII 
FOOD  AND  DIGESTION        ........    I38 

CHAPTER  VIII 
THE  NERVOUS  SYSTEM      ........    l84 

CHAPTER  IX 
THE  SENSES       ..........    *3 

NOTES  ON  SANITATION      ........    2^7 

GLOSSARY  ........       ...    268 

INDEX  .....        .....    271 


LESSONS   IN   HYGIENIC   PHYSIOLOGY 


CHAPTER   I 

INTRODUCTION 

PERHAPS  you  have  studied  Physiology  and  Hygiene 
before,  and  if  you  were  asked  how  does  the  body  grow, 
you  could  readily  answer.  You  would  say,  "The  food 
nourishes  the  body  and  enables  it  to  grow."  But  if  you 
were  asked  how  does  the  food  enable  the  body  to  grow,  you 
could  not  answer.  If  you  were  asked  how  a  cut  in  the 
skin  is  healed,  you  would  say  that  the  blood  brings  the 
nourishment  to  the  skin ;  but  you  have,  as  yet,  no  idea  as 
to  hoiv  the  skin  uses  this  nourishment  to  heal  the  cut. 

If  you  were  asked  how  is  it  that  the  body  is  always 
warm,  even  on  the  coldest  winter  day,  you  would  say  that 
the  oxygen,  so  abundant  in  pure  air,  is  taken  into  the  body 
through  the  lungs,  and  burns  the  food.  But  where  is  the 
fire  ?  Is  it  in  the  blood,  or  in  the  muscles  ?  What  regulates 
the  burning  ?  What  regulates  the  use  of  the  food  after  it 
has  been  digested,  and  of  the  oxygen  after  the  lungs  have 
furnished  it  to  the  blood?  In  order  that  you  may  better 
understand  these  things,  you  will  now  study  physiology 
from  a  new  point  of  view.  You  must  study  something  of 
the  tissues  of  the  body  and  how  these  tissues  live  and  grow. 
But  let  us  not  forget  for  a  moment  that  there  are  many 
mysteries  about  life  that  man  never  has  solved  and  never 


2  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

will  solve.  To  help  us  to  understand  more  about  man's 
body,  we  will  first  compare  man  with  other  animals. 

Which  is  more  like  a  Man,  a  Crawfish  or  a  Bird  ?  —  You 
reply,  "  A  bird  is  more  like  a  man."  But  why  do  you  say 
so,  although  a  bird  has  wings  ?  You  answer,  "  Because 
the  bones  and  blood  of  a  bird  are  more  like  those  of  a  man 
than  are  such  parts  of  a  crawfish." 

Which  is  more  like  a  Man,  a  Bird  or  a  Beast  —  for 
example,  a  horse  ?  You  say  the  horse  is  more  like  a  man. 
A  horse  has  hair ;  a  bird  has  none.  A  bird  lays  eggs ; 
a  horse  does  not.  A  horse  has  teeth;  a  bird  has  none. 

Which  is  more  like  a  Man,  a  Horse  or  a  Dog? — You 
are  not  so  quick  in  replying  this  time.  A  dog  and  a  horse 
are  about  equally  intelligent,  both  have  four  legs  and  no 
hands ;  but  by  close  examination  you  see  that  the  teeth 
of  one  are  more  like  a  man's  teeth  than  are  those  of  the 
other ;  that  a  dog  has  claws  on  his  feet,  and  a  horse  has 
nails,  although,  indeed,  the  latter  has  only  one  toenail  on 
each  foot  —  a  very  large  one  called  a  hoof.  But  whether 
you  think  a  dog  or  a  horse  is  more  like  a  man,  you  know 
that  they  are  both  more  like  a  man  than  is  a  bird  or  a 
crawfish. 

There  are  other  animals  that  are  even  less  like  ourselves 
than  those  which  have  been  mentioned.  There  are  the 
insects,  or  animals  with  six  legs  and  the  body  in  three  parts, 
like  the  wasp,  the  ant,  the  grasshopper.  There  are  the 
earthworms  with  no  legs  at  all,  the  oysters  and  clams,  the 
starfish,  the  sponges,  the  small  coral  animals. 

But  of  all  the  animal  kingdom,  the  animals  that  are 
most  different  from  man  are  the  minute  creatures  that  can 
be  seen  only  with  a  microscope.  They  are  so  small  that  it 
takes  thousands  of  them  to  make  a  mass  as  large  as  the 
head  of  a  pin.  In  fact,  some  of  the  pupils  may  ask,  "Are 


INTRODUCTION 


psd 


magnified. 
nuf  nucleus;  psdt  false  foot. 


such  creatures  animals  at  all?"     Certainly,  for  they  are 

neither  vegetables  nor  minerals. 

The  Ameba.  —  One  of   the   most  interesting  of  these 

microscopic  animals,  and  one  that  is  very  easy  to  find 

with  the  aid  of  a  microscope,  is 

the  a-me'-ba  (Fig.  I ;  spelled 
also  amoeba).  We 
have  only  to  place 
some  dead  grass 
in  a  vessel  of 
water,  and  let  it 
stand  for  a  few 
days,  when,  if  we  look 

through  a  microscope,  FIG.  i.  -  AN  AMEBA,  highly 
we  shall  be   likely  to 
find  amebas  in  a  drop 

of  the  water.  A  thousand  of  them  placed  in  a 
row  would  hardly  reach  an  inch.  Some  may 
doubt  whether  the  ameba  is  a  complete  ani- 
mal. Study  the  figures  of  it,  and  you  can 
find  no  head,  or  arms,  or  legs,  or  mouth.  It 
appears,  when  still,  to  be  merely  a  lump  of 
jelly.  But  the  ameba  can  push  out  any  part 
of  its  body  as  a  foot,  and  move  slowly  by 
rolling  its  body  into  the  foot.  //  can  put  out 
any  part  of  its  body  as  an  arm,  and  take  in 
(J  a  speck  of  food ;  or,  if  the  food  happens  to 
be  near,  the  ameba  can  make  a  mouth  by 
drawing  in  any  part  of  its  body,  and  then 
AMEBA  tak-  swallow  the  food  by  closing  around  it.  See 
the  pictures  (Fig.  2).  The  ameba  has  no 

lungs,  but  breathes  with  all  the  surface  of  its  body.     Any 

part  of  its  body  can  do  anything  that  another  part  can  do. 


FIG.  2.  —  THE 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


When  the  ameba  grows  to  a  certain  size,  it  multiplies  by 

squeezing  together  near  the  middle  (see  Fig.  3)  and  divid- 
ing into  two  parts. 

The  Ameba  and  Man  Compared.  —  The 
microscope  shows  us  that  the  skin,  the  mus- 
cles, the  blood,  —  in  fact,  all  parts  of  the 
body,  — contain  numberless  small  parts  called 
cells.  These  cells  are  continually  changing 
with  the  activities  of  the  body.  One  of  the 
most  interesting  kinds  of  cells  we  shall  find 
to  be  the  white  blood  cells,  or  corpuscles. 
One  is  shown  in  Figure  4,  with  the  changes 
that  it  had  undergone  at  intervals  of  one 
minute.  The  thought  will  readily  occur  to 
you  that  these  cells,  although  part  of  man's 
body,  resemble  the  ameba  that  lives  an  inde- 
pendent life.  The  cells  in  the  body  have 
some  resemblance  to  the  one-celled  animals, 
of  which  the  ameba,  that  has  been  described, 
is  a  type.  You  will  now  begin  to  see  what 
is  meant  by  the  statement  that  a  man  or  a 
horse  or  a  fish  —  in  fact,  any  large  animal  — 

has  something  of  the  nature  of  a  colony,  or  collection,  of 

one-celled  animals.     You  are  now  prepared  to  understand 

a  little  as  to  how  the 

body  grows,  and  how 

a  cut  in  the  skin 'is 

repaired.      The  cells 

take  the  nourishment 

brought  by  the  blood, 

use  it,  and  grow  and  multiply  like  the  ameba.     Thus  new 

tissue  is  formed.     All  animals  and  vegetables — that  is  to 

say,  all  living  things  —  are  made  of  cells. 


FIG. 3.— A  CELL 

dividing    into 

two  cells. 


FIG.  4.  — A  WHITE  BLOOD  CELL,  magnified; 
forms  noticed  at  intervals  of  one  minute. 


INTRODUCTION 


A  living  cell  always  contains  a  still  smaller  body,  called  a 
nucleus  (Fig.  5).  There  is  sometimes  a  small  dot  in  the 
nucleus  called  the  nucleolus.  The  main  body  of  the  cell 
consists  of  a  living  substance  called  protoplasm.  Usually, 
but  not  always,  there  is  a  wall  surround- 
ing the  cell,  called  the  cell  wall. 
Workers  with  the  microscope  found 
long  ago  that  animals  and  plants  are 
constructed  of  little  chambers  which 
they  called  cells.  It  was  found  later 
that  the  soft  contents  in  the  little 
chambers  is  of  more  importance  than 
the  walls  which  the  protoplasm  builds 
around  itself.  A  living  cell  is  not  like 

. 

a  cell  in  a  honeycomb  or  a  prison.     In 

the  study  of  animals  and  plants  we  define  a  cell  as  a  bit 

of  protoplasm  containing  a  nucleus. 

A  fiber  is  threadlike,  and  is  either  a  slender  cell  (Fig. 
6),  a  slender  row  of  cells  (Fig.  9),  or  a  branch  of  a  cell.  A 
tissue  is  defined  as  a  network  of  fibers  or  a  mass  of  similar 


FIG.   5. —  DIAGRAM  OF 
A  CELL. 

/,  protoplasm  (complex  in 
structure);  «,  nucleus; 
«',  nucleolus. 


FlG.  6.  —  A  CELL  so  slender  that  it  is  called  a.  fiber. 
«,  nucleus  (from  involuntary  muscle  around  intestine). 

cells  serving"  the  same  purpose,  or  doing  the  same  work.    A 
membrane  is  a  thin,  skinlike  tissue  (Fig.  7). 

A  New  Insight  into  the  Nature  of  the  Human  Body.  — 
The  human  body  is  a  community  of  cells,  and  may  be  com- 
pared to  a  community  of  people.  It  is  a  crowded  commu- 
nity, for  all  the  citizens  live  side  by  side  as  they  work. 
They  are  so  small  that  it  takes  several  hundred  of  them  to 
make  a  line  an  inch  long.  We  should  never  have  sus- 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


pected  the  existence  of  cells  had  it  not  been  for  the 
microscope ;  but  now  we  know  that  they  eat  and  breathe 
and  work  and  divide  into  young  cells 
which  take  the  place  of  the  old  ones. 

A  child  that  is  born  in  a  community 
of  people  may  become  a  railroad  man  and 
carry  food  and  other  freight  from  place 
to  place ;  so  in  the  great  community  of 
cells  (see  Fig.  8)  making  up  the  human 
body,  the  red  blood  cells,  like  the  railroad 
man,  are  employed  in  carrying  material 
from  place  to  place.  But  the  community 
is  old-fashioned,  for  the  citizens  build 
canals  instead  of  railroads  for  their  com- 
merce (see  Fig.  84).  Just  as  a  child 
may  grow  up  to  be  a  farmer  and  aid  in 
FIG.  7.  — MUCOUS  MEM-  the  conversion  of  crude  soil  into  things 

BRANE  formed  of  one 

layer  of  cells.    A  few  suitable  for  the  use  of  man,  so  the  diges- 

cells  secrete  mucus.  the  fo()d  we 


it  into  material  with  which  the  cells  can  build  tissue  (see 
Fig.  7).  Some  of  the 
citizens  of  a  commu- 
nity must,  at  times, 
take  the  part  of  sol- 
diers and  policemen, 
and  protect  the  com- 
munity against  the 
attack  of  enemies ;  we 
even  find  in  the  com- 
munity of  cells  those 

which  have  this  duty.    FIG.  8.— VARIOUS  CELLS  of  the  body.     (Jegi.) 
.  Tiny  citizens  of  the  bodily  community. 

ihe  white  blood  cells, 

already  referred  to,  may  be  called  the  soldiers;  for  they 


INTRODUCTION  7 

go  to  any  part  attacked  by  injurious  germs,  a  speck  of 
poison,  or  other  enemy,  and  try  to  destroy  the  enemies 
by  devouring  or  digesting  them.  At  other  times  they 
help  to  repair  a  break  in  the  skin.  If  a  splinter  gets 
into  the  skin,  the  white  blood  cells  form  a  white  pus 
around  the  splinter  and  remove  it.  In  fact,  the  white 
blood  cell  has  been  referred  to  as  a  kind  of  Jack-at-all- 
trades.  In  the  human  community  there  are  certain  per- 
sons who  reach  the  positions  of  teachers,  lawmakers,  and 
governors ;  they  instruct  and  direct  the  other  members  of 
the  community.  Just  so,  in  the  community  of  cells,  there 
are  certain  cells  called  nerve  cells  (see  Fig.  10)  that  have 
the  duty  of  governing  and  directing  the  other  cells.  The 
nerve  cells  are  most  abundant  in  the  brain.  Large  cities 
have  many  scavengers.  Likewise  in  the  human  body,  a 
community  composed  of  millions  of  cells,  there  are  certain 
cells  in  the  skin  and  the  kidneys  which  have  this  duty.  They 
are  continually  removing  impurities  from  the  body. 

Division  of  Labor.  —  There  is  a  great  advantage  in  each 
cell  of  the  human  body  having  its  special  work,  instead  of 
having  to  do  everything  for  itself,  as  each  ameba  cell  must 
do.  Under  this  system  each  cell  can  do  its  own  work  better 
than  a  cell  of  any  other  kind  can  do  it.  Among  wild  tribes 
there  is  very  little  division  of  labor.  Each  man  makes  his 
own  weapons,  each  knows  how  to  weave  coarse  cloth,  how 
to  cook,  how  to  farm,  etc.  Savages  do  not  have  as  good 
weapons  as  do  people  who  leave  the  making  of  weapons  to 
certain  men  whose  special  business  it  is.  What  kind  of 
pocketknives  or  pencils  do  you  think  the  boys  of  this 
country  would  have  if  each  boy  had  to  make  his  own 
pocketknife  or  pencil  ?  What  kind  of  scissors  and  thread 
would  the  girls  have  if  each  girl  had  to  make  them  her- 
self ?  Our  muscle  cells  can  contract  better  than  the 


8  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

ameba;  the  cells  in  the  lungs  can  absorb  oxygen  better 
than  the  ameba.  We  have  just  as  great  an  advantage  in 
digestion,  feeling,  and  other  processes  ;  for  the  ameba  eats 
without  a  mouth,  digests  without  a  stomach,  feels  without 
nerves,  breathes  without  lungs,  and  moves  without  muscles. 

Definitions.  — In  each  chapter  of  this  book  you  will  study 
a  certain  part  of  the  body,  learn  where  it  is,  how  it  looks, 
and  how  it  is  constructed ;  this  is  anatomy.  In  the  same 
chapter  you  will  study  the  use  of  the  part ;  this  is  physi- 
ology. Lastly,  you  will  learn  how  to  take  care  of  each 
part ;  this  is  hygiene.  A  part  of  the  body  which  is  some- 
what separate  from  surrounding  parts,  and  has  special  work 
to  do,  is  called  an  organ;  the  special  work  which  the  or- 
gan does  is  called  its  function.  The  eye  is  the  organ  of 
sight.  The  skin  is  an  organ  ;  its  function  is  to  protect  the 
body.  Supply  the  words  "anatomy,"  "physiology,"  and 

"  hygiene  "  in  their  proper  places  in  this  sentence :  

treats  of  health  ; treats  of  functions  ; treats  of  the 

structure  of  the  body.  Everything  in  the  world  belongs 
to  one  of  three  kingdoms,  —  animal,  vegetable,  or  mineral. 
Animals  and  vegetables  have  organs  and  are  placed  to- 
gether in  the  organic  kingdom.  Minerals  have  no  organs 
and  are  said  to  be  in  the  inorganic  kingdom.  The  chief 
difference  between  animals  and  plants  is  that  plants  get 
their  food  from  the  mineral  kingdom  and  animals  get  their 
food  from  the  vegetable  kingdom. 

The  Tissues.  —  As  the  organs  have  different  functions, 
they  mtist  have  different  structures  that  they  may  be  adapted 
to  their  work.  Just  as  a  house  must  have  brick  for  the 
chimney,  shingles  for  the  roof,  and  nails  to  hold  the  tim- 
bers and  other  parts  together,  so  the  body  has  various 
tissues  to  serve  different  purposes.  The  bones  must  not 
be  constructed  like  the  muscles,  and  the  muscles  cannot 


INTRODUCTION 


be  like  the  skin.  The  chief  work  of 
the  cells  is  to  construct  the  tissues  and 
repair  them.  During  life  changes  are 
constantly  going  on.  Careful  little 
workmen  are  keeping  watch  over 
every  part  of  the  body  ;  nimble  little 
builders  are  busy  in  repairing  and 
restoring.  No  sooner  is  one  particle 
removed  than  another  takes  its  place. 
In  one  direction  the  cells,  acting  as 
sextons,  are  hurrying  away  matter 
which  is  dead  ;  in  the  other  direction 
the  unseen  builders  are  filling  the  va- 
cant places  with  matter  that  is  living. 

The  Seven  Tissues.  —  There  are 
seven  kinds  of  tissues.  Two  of  them, 
the  muscular  and  nervous  tissues,  are 
called  the  master  tissues,  since  they 
control  and  expend  the  energies  of  the 
body.  The  other  five  tissues  are  called 
the  supporting  tissues,  since  they  sup- 
ply the  energy  to  the  master  tissues, 
support  them  in  place,  nourish  and 
protect  them. 

The  Master  Tissues.  — The  muscu- 
lar tissue  consists  chiefly  of  rows  of 
cells  placed  end  to  end  (Fig.  9).  These 
cells  have  the  remarkable  property  of 
becoming  broader  and  shorter  when 
stimulated  by  impulses  from  nerve 
cells. 

The  nerve  tissue  consists  of  cells 
with  long,  spiderlike  branches  (Fig. 


FIG.  9.  — THREE  MUSCLE 
FIBERS  from  the  heart 
(showing  the  nuclei  of 
six  cells). 


FIG.  io.  — NERVE  CELLS, 
showing  their  brandies 
interlacing. 


10 


LESSONS  JN  HYGIENIC  PHYSIOLOGY 


10).  Some  nerve  cells  have  branches  several  feet  long:  so 
long  that  they  go  from  the  backbone  to  the  foot.  The 
branches  are  called  nerve  fibers  (Fig.  142).  They  are  so 
small  as  to  be  invisible  to  the  unaided  eye,  but  a  number 
of  fibers  from  different  nerve  cells  are  usually  bound 
together,  forming  a  thread  called  a  netve,  which  is  large 

enough  to  be  seen.  The  great- 
est  collection  of  nerve  cells  in 
^e  body  is  in  the  head  and  is 
called  the  brain.  The  largest 
nerve  in  the  body  leads  from 
t^ie  krain,  and  *s  called  the 

spinal  cord.    It  occupies  a  tube 
FIG.  ii.—  CONNECTIVE  TISSUE  CELLS  ,  ,       ,     ;•    ,  i  r~, 

removed  from  among  the  fibers  of  formed  by  the  backbone.    The 

Figurel2' 


,  c,  nucleus;  /,  branches. 


spinal  cord  is  not  made  of 
fibers  alone,  for  it  contains 
many  nerve  cells  also.  Did 
you  ever  notice  the  spinal  cord 
of  a  hog  ?  Describe  the  brain 
of  a  hog  or  an  ox,  if  you  ever 
saw  one.  A  human  brain  has 
the  same  general  appearance. 
Nerve  fibers  which  carry  im- 
pulses to  the  nerve  cells  are 
called  sensory  fibers.  When 
the  other  cells  are  hungry  or 
tired,  they  let  the  brain  know 
through  the  sensory  fibers. 
The  nerve  fibers  which  carry 

a,  6,  bundles  of  white  fibers;   c,  a  yellow    impulses    from   the   nerVC   Cells 
fiber. 

are  called  motor  fibers.     The 

organs  are  set  to  work  by  impulses  through  the  motor 
fibers.     You  will  next  study  the  five  supporting  tissues. 


FIG.  12.  —  CONNECTIVE  TISSUE 
FIBERS. 


INTRODUCTION 


II 


Connective  tissue,  like  all  other  tissues,  contains  cells 
(see  Fig.  n),  but  it 
consists  chiefly  of  fine 
fibers.  These  fibers  are 
of  two  kinds,  —  very  fine 
white  fibers  which  are 
inelastic,  and  larger  yel- 
low fibers  which  are  very 
etas  tic  (see  Fig.  1 2).  Con- 
nective tissue  is  found  in 
every  organ,  binding  to- 
gether the  other  tissues 
and  cells.  It  is  inter- 
woven among  the  mus- 
cle cells,  and  the  tendons 
at  the  ends  of  the  mus- 
cles are  composed  almost 
wholly  of  it.  If  every 
other  tissue  were  re- 
moved, the  connective 

tissue  would  still  give  a  perfect  model  of 
all  the  organs.  How  abundant  this  tis- 
sue is  in  the  skin  may  be  known  from  the 
fact  that  leather  consists  entirely  of  it. 

Fatty  (Adipose)  Tissue. — Fatty  tissue  is 
formed  by  the  deposit  of 
oil  in  connective  tissue 
cells  (see  Fig.  1 3).  Fat  is 
held  in  meshes  of  connec-  FIG.  15.— Six  GLAND 
Fir,  14. -EPITHELIAL  tive  tissue  fibers.    That 

TISSUE;    cells  form- 
ing  two  glands  in  fatty  tissue  consists  not 

wall  of  stomach.  ,         r  r       ,  r  rt 

only  of  fat  but  of  fibers 
also,  is  shown  when  hog  fat  is  rendered  into  lard,  certain 


FIG.  13.  —  FATTY  TISSUE.     Five  fat  cells,  held 
in  bundles  of  connective  tissue  fibers. 

a  is  a  large  oil  drop;  m,  cell  wall;  nucleus  («) 
and  protoplasm  (/)  have  been  pushed  aside  by 
oil  drop  (a). 


CELLS,  shrunken 
after  activity ;  (at 
right)  rested,  full  of 
granules. 


12 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


tough  parts  called  "cracklings"  being  left.  What  is  the 
difference  between  beef  fat  and  tallow  ? 
Epithelial  tissue  consists  of  one  or 
more  layers  of  distinct  cells  packed  close 
together  (see  Fig.  16).  It  contains  no 
connective  tissue  or  other  fibers,  and  is 
the  simplest  of  the  tissues.  Epithelial 
tissue  forms  the  outer  layer  of  the  skin, 
called  the  epidermis,  and  the  mucous 
membrane  lining  the  interior  of  the  body 
(Fig.  7).  It  contains  no  blood  vessels, 

1.].^  epithelial  cells  obtaining  their  nourish- 
FIG.  16.  —  EPITHELIAL 

TISSUE     (epidermis    went  from  the  watery 
of  skin).  portion  of  the  blood 

which  soaks  through  the  underlying  tis- 
sue.    Epithelial  cells  are  usually  trans- 
parent ;  for  instance,  the  blood  is  visible 
beneath  the  mucous  membrane  of 
the    lips.       The   finger    nails    are 
made  of  epithelial  cells,  and  they 

are  nearly  transparent.  FIG.  18.—  GL\NDS  shaped  like 

One  class  of  epithelial  cells  form 

^         ••••7l         protective  coverings  (Fig.   16);  the 
zii-i  „  .-'0'^  \  other  class  form  the  lining  of  glands 

,  .^K^-:  (Fig.  14).   Glands  are  cavities  (Figs. 

17,  1  8)  whose  walls  (Fig.  14)  form 
either  useful  fluids  called  secretions 
tc  aid  the  body  in  its  work,  or  harm- 
f  ul  fluids  called  excretions  to  be  cast 
out.  Most  glands  empty  their  fluids 


FIG.    17.  —  GLANDS   in 
the  form  of  tubes. 


FIG.  19.—  CARTILAGINOUS  Tis-  . 

SUE.     A  thin  slice  highly  through  tubes  called  ducts. 

magnified- 

*,&,c,  groups  of  cells;    mt  inter-  ,.,-..,  . 

ceiiuhu  substance.  elastic.     Cartilage  or  gristle  may 


Cartilag'inous  tissue>  tough,  yet 


INTRODUCTION 


be  readily  felt  in  the  ears,  the  windpipe,  and  the  lower 
half  of  the  nose.  This  tissue  consists  of  cartilage  cells 
embedded  in  an  intercellular  substance  through  wJiich  run 
connective  tissue  fi bcrs  (see  Fig.  19).  If  yellow  fibers  pre- 
dominate, the  cartilage  is  yellow 
and  very  elastic,  as  in  the  ear ;  if 
white  fibers  predominate,  it  is  white 
and  less  elastic,  as  in  the  pads  of 
gristle  between  the  bones  of  the 
spinal  column.  Cartilage  is  to  pre- 
vent jars,  and,  in  movable  joints, 
to  prevent  friction. 

Bony  (Osseous)  Tissue.  —  Appar- 
ently solid  bone  is  seen  under  the 
microscope  to  contain  many  minute 
cavities  (Fig.  20).  In  these  cavities 
tJie  bone  cells  lie  self-imprisoned  in 
walls  of  stone  ;  for  these  cells  have 
formed  the  bone  by  depositing  lime-  Larger  blood  tubes  pass  through  the 
stone  and  phosphate  of  lime  around 
themselves.  There  are  minute  ca- 
nals  (3,  Fig.  20),  however,  through 

which  nourishment  comes  to  the  cells.  The  watery  por- 
tion of  the  blood  passes  through  these  small  canals  from  the 
blood  vessels  that  flow  through  the  larger  canals  (i,  Fig. 
20).  Bone  cells  may  live  for  years,  although  some  of  the 
other  cells  of  the  body  live  only  a  few  hours. 

THOUGHT  QUESTIONS.  —  Value  of  Health.  1.  Write  five  blessings 
in  youth  or  later  in  life  that  result  from  good  health.  2.  Write  five 
things  that  most  people  value  more  than  health,  since  some  people 
lose  their  health  to  obtain  them.  3.  Write  five  results  of  sickness. 
4.  Think  of  ten  grown  persons  at  random.  How  many  of  them  are 
in  sound  health  ?  5.  What  proportion  of  people  live  out  "  threescore 
and  ten  "  years  ? 


FIG.  20.  — BONY  TISSUE.  Thin 
slice  across  bone. 


14  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

The  body  is  kept  alive  and  warm  by  burning,  or  oxida- 
tion. Oxygen  gas  is  a  part  of  the  air.  We  breathe  it 
in  every  minute  of  our  existence.  It  is  carried  by  the 
blood  to  all  the  tissues.  Not  one  of  the  cells  could  work 
without  oxygen.  Without  it  the  body  would  soon  be  cold 
and  dead,  for  oxygen  keeps  the  body  alive  and  warm  by 
uniting  in  the  cells  with  sugar,  fat,  and  all  other  sub- 
stances in  the  body  except  water  and  salt.  Oxygen  burns 
or  consumes  the  substances  with  which  it  unites,  and  the 
process  is  called  oxidation.  Hence  the  cells  have  to  be 
continually  growing  and  multiplying  to  repair  the  tissue 
and  replace  the  material  used  up  by  oxidation.  Sugar  and 
flour  and  fat  oxidize,  or  burn,  outside  of  the  body,  as  well 
as  in  it,  as  can  be  proved  by  throwing  them  into  a  fire. 
Water  and  salt  are  two  foods  that  do  not  burn  in  the  body. 
Water  puts  out  a  fire  instead  of  helping  it,  and  so  does  salt. 
You  may  have  thrown  salt  into  a  fire  or  on  a  stove  and 
noticed  that  it  popped  like  sand,  but  did  not  burn. 

The  cells  need  the  oxygen  of  fresh  air ;  they  need  food 
for  the  oxygen  to  unite  with,  but  they  are  injured  by  many 
substances  called  poisons.  Arsenic  destroys  the  red  blood 
cells.  Strychnine  attacks  the  nerve  cells  in  the  spinal  cord. 
Alcohol  attacks  the  epithelial  cells  lining  the  stomach  and, 
when  it  is  absorbed,  attacks  the  nerve  cells  (see  Fig.  160) 
and  other  cells.  Morphine  attacks  the  nerve  cells.  These 
substances  are  poisons.  Wine  and  beer  contain  the  poi- 
son called  alcohol.  Tobacco  contains  a  poison  called 
nicotin. 

Experiments.  —  i.  Light  a  candle  and  bring  a  glass  pickle 
jar  down  over  it.  What  happens  ?  Why  ?  2.  Pass  a  glass 
tube  or  a  long  straw  or  the  hollow  stem  of  a  weed  into  a 
jar  through  a  hole  in  a  piece  of  cardboard.  Send  one  long 
breath  into  the  jar.  Place  the  jar  mouth  downward  on  a 


INTRODUCTION  15 

table.  Slip  the  cardboard  away.  Slide  the  jar  to  the  edge 
of  the  table  and  pass  a  lighted  candle  into  it.  What  hap- 
pens ?  A  gas  called  carbon  dioxid  is  formed  by  fires  and 
by  oxidation  in  our  bodies.  This  gas  smothers  a  fire  and 
destroys  life. 

THOUGHT  QUESTIONS.  —  The  Tissues.  1.  Which  tissue  has  the 
largest  proportion  of  substance  between  the  cells  ?  (Fig.  20.) 
2.  Which  tissue  has  no  fibers,  but  is  composed  almost  wholly  of 
cells  ?  3.  Which  tissues  have  cells  without  branches  ?  With 
branches  ?  4.  Does  fat  accumulate  in  the  body  within  the  cells  or 
outside  of  them  ?  5.  How  does  blood  resemble  a  tissue  ?  (Fig.  76.) 
6.  Which  cell  has  the  greatest  variety  of  functions  ?  Which  cells  are 
very  active  ;  which  moderately  active  ;  which  very  inactive  ?  7.  Give 
an  instance  of  a  cell  of  one  kind  of  tissue  becoming  a  cell  of  another 
kind  of  tissue  (Fig.  13).  8.  How  does  a  tissue  grow  ?  Does  a  scar 
on  a  child  enlarge  as  its  body  grows  ?  9.  The  elasticity  of  the  skin 
suggests  that  it  contains  what  kind  of  fibers  ? 

WRITTEN  EXERCISES.  —  Draw  a  series  of  seven  pictures  to  show  the 
seven  tissues  (Figs.  9,  10,  12,  13,  16,  19,  20).  Write  the  "Autobi- 
ography" of  a  White  Blood  Cell  (see  also  pages  97  and  128).  The 
Rewards  of  Caring  for  the  Health.  A  Railway  Wreck  caused  by 
Alcohol  (description  and  reflections).  Health  and  the  Disposition. 
Which  is  more  Important,  a  Thorough  Knowledge  of  Geography  or 
of  Physiology? 


CHAPTER  II 
THE  SKIN 

The  Chief  Function  of  the  Skin.  —  The  skin  has  several 
functions,  or  uses.  The  one  which  is  most  easily  seen  is 
that  of  protection  of  the  organs  below  it.  The  skin  is 
thickest  on  the  palms  of  the  hands  and  on  the  soles  of  the 
feet,  where  protection  is  most  necessary.  It  is  thinnest  at 
the  joints  and  wherever  rapid  motion  is  required,  as  over 
the  eyelids.  At  the  ends  of  the  fingers  and  toes,  where 
unusual  protection  is  needed,  it  grows  into  shieldlike plates 
called  nails.  On  the  head  the  skin  puts  forth  a  thick  cov- 
ering of  hair  which  aids  the  skull  in  protecting  the  delicate 
brain.  A  strong  suit  of  clothes  is  a  good  protection  for 
the  body ;  but  the  skin  is  even  a  better  protection,  for  it 
has  the  special  adaptations  just  mentioned,  and  is  stronger 
than  one  might  suppose  from  its  appearance. 

That  the  skin  is  capable  of  great  stretching  is  shown  in 
cases  of  the  dropsy;  that  it  will  not  contract  beyond  a 
certain  limit  is  shown  by  the  wrinkles  of  very  lean  or  old 
people. 

General  Structure  of  the  Skin.  —  If  you  pinch  up  a  fold 
of  the  skin  on  the  back  of  the  hand,  you  will  notice  that  the 
skin  there  is  about  one  tenth  of  an  inch  thick,  the  fold 
showing  a  double  thickness.  When  a  person  burns  him- 
self so  as  to  make  a  blister,  the  outer  layer  of  the  skin  is 
separated  from  the  skin  below.  The  covering  of  the  blis- 
ter is  much  thinner  than  the  skin,  being  hardly  thicker 

10 


THE  SKIN  I/ 

than  paper;  neither  is  it  so  elastic  as  the  fold  of  skin 
tested  on  the  back  of  the  hand.  It  is  much  lighter  in 
color,  and  is  not  sensitive  like  the  pink  and  tender  layer 
seen  beneath  the  blister.  Hence  we  conclude  that  the 
skin  must  be  in  two  layers.  This  outer  layer  is  called  the 


FIG.  21.  — SECTION  OF  SKIN,  highly  magnified.    (Cunningham.) 

epidermis ;  it  is  thinner,  more  transparent ',  and  less  elastic  ' 
than  the  inner  layer,  or  dermis.  The  epidermis  is  com- 
posed of  epithelial  cells  packed  close  together  (see  Fig.  22). 
The  dermis,  or  inner  layer,  is  a  closely  woven  sheet  of  con- 
nective tissue  containing  a  great  number  of  sweat  and  oil 
glands,  roots  of  hairs,  blood  vessels,  absorbent  vessels 
(lymphatics),  and  nerves  (see  Fig.  21).  The  dermis  is 


18 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


sometimes  called  the  true  skin  because  it  is  of  greater 
importance  than  the  epidermis.  It  is  united  loosely  to 
the  underlying  organs  by  a  layer  of  connective  tissue.  It 
is  in  this  layer  that  fat  is  stored. 

Papilla.  —  The  upper  surface  of  the  dermis  rises  into  a 
multitude  of  projections  (see  Fig.  22,  also  colored  Fig.  14) 


Z  (  Horny  layet 


Epidermis 


Papillae  of 
dermis  con- 
taining blood 
vessels 


Dermis<       WT-. 


FIG.  22.— SECTION  OF  EPIDERMIS,  with  papillae  of  dermis. 

called  papiVlcz  (singular,  papilla).  The  epidermis  fits 
closely  over  them  and  completely  levels  up  the  spaces 
between  them  except  on  the  palms  and  the  soles.  Here 
the  papillae  are  in  rows,  and  there  is  a  fine  ridge  in  the  skin 
above  each  row  of  papillae  (Fig.  29).  In  the  papillae  are 
small  loops  of  blood  vessels  and  sometimes  a  nerve  fiber. 


THE  SKIN 


The  epidermis  is  composed  of  a  mass  of  cells  held  to- 
gether by  a  cement  resembling  the  white  of  an  egg.  The 
cells  near  the  surface  are  hard  and  flattened  ;  those  deeper 
down  near  the  dermis  are  round  and  soft  (see  Fig.  22). 
These  cells  are  living  cells.  They  are  kept  alive  by  the 
nourishment  in  the  watery  portion  of  the  blood  which 
soaks  through  from  the  blood  tubes  in  the  neighboring 
papillae.  Hence  these  cells  are  growing  cells  ;  they  sub- 
divide when  they  reach  a  certain  size,  and  replace  those 
wearing  away  at  the  surface,  thus  constantly  repairing  the 
epidermis.  The  dry  outer  cells  wear  away  rapidly.  They 
have  no  nuclei  and  are  dead  cells.  The  new  cells  forming 
beneath  push  them  so  far  away  from  the  dermis  that  nour- 
ishment no  longer  reaches  them,  and  they  die. 

Pigment.  —  The  cells  in  the  lower  layers  of  the  epidermis 
contain  grains  of  coloring  matter,  or  pigment.  Africans 
have  dark  and  abun- 
dant pigment  (Figs. 
23,  24).  The  varying 
amount  and  tint  of 
the  pigment  cause  the 
red  skin  of  the  Indian 
race,  the  yellow  skin 
of  the  Chinese,  the 
brown  skin  of  the  Ma- 
lay. The  pigment  in 
neighboring  cells 
sometimes  develops 
to  a  marked  degree 
and  forms  what  is 
called  a  freckle.  Al- 
binos, or  persons  entirely  without  pigment,  have  pallid  com- 
plexions and  pink  eyes.  They  are  found  in  all  races  ;  there 


FIG.  23.  — EPIDERMIS 
OF  NEGRO. 


FIG.  24.  — EPIDERMIS 
OF  CAUCASIAN. 


20 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


are  some  Albino  negroes.  Is  the  pigment  in  the  cells  or 
between  them  ?  (See  Fig.  22.)  The  amount  of  pigment 
is  increased  by  long  exposure  to  sunlight.  This  effect  is 
noticeable  at  the  wrists.  The  sunlight  is  also  a  great 
purifier  of  the  skin.  So  a  person  who  never  exposes  the 
skin  to  sunlight  is  likely  to  have  a  dark  or  dingy  skin  from 
the  impurities  in  it,  or  because  the  blood  circulating 
through  it  is  dark  and  impure. 

The  hair  is  really  the  epidermis  grown  into  fine  rods  or 
threads.  Each  hair  grows  from  a  moldlike  papilla  called 
a  hair  bulb,  which,  unlike  ordinary 
papillae,  is  at  the  bottom  of  a  little 
pit  called  a  hair  follicle  (see  Fig.  25). 
The  cap  of  epidermis  formed  on 
,d  such  a  papilla  does  not  fall  off,  but 
remains,  and  new  cells  are  formed 
beneath  it  until  the  cap  is  pushed  up 
into  a  long,  slender  rod  of  epidermis 
(Fig.  26).  In  old  age  the  pigment 
in  the  hair  is  replaced  by  air.  The 
use  of  dye  upon  gray  hair  is  in  bad 
taste  and  is  now  seldom  seen.  One 
or  more  oil  glands  open  into  each 
FIG.  25.— TWO  HAIRS  IN  follicle  (see  Fig.  25). 

Blood  vessels  and  a   nerve  fiber 

at  oil  glands  ;  et  sweat  glands. 

go  to  the   root  or   bulb  from  which 

the  hair  grows.  The  hair  will  grow  until  this  papilla, 
or  bulb,  is  destroyed.  It  is  impossible  to  stop  the  growth 
of  superfluous  hair  unless  the  hair  papillae  are  destroyed 
with  an  electric  'needle,  such  is  the  vitality  of  hair ; 
yet  many  men,  by  overheating  the  head  and  cutting  off 
the  circulation  with  tight  hats,  destroy  much  of  the  hair 
before  reaching  middle  age.  The  health  of  the  hair  can- 


THE  SKIN 


21 


is. 


not  be  restored  except  by  going  bareheaded  most  of  the 
time.  This  frees  the  circulation,  and  the  sunlight  and 
cold  air  stimulate  the  cells 
of  the  scalp.  The  hairs,  or 
rather  the  follicles  around 
them,  are  provided  with 
tiny  muscles  with  which  the 
hairs  are  made  to  stand  on 
end  (Fig.  21).  Why  does 
trimming  the  ends  of  the 
hair  have  no  effect  upon  its 
growth  ?  Why  is  pulling 
the  hair  painful,  while  cut- 
ting it  is  not  felt  ? 

Experiment  3.  The  mi- 
nute hairs  scattered  over 
the  body  aid  greatly  in 
touch.  Let  a  classmate 
rest  his  hand  upon  the 
back  of  the  desk,  while  you 
touch  a  hair  on  his  hand 
to  find  whether  or  not  he 
can  feel  it. 

The  uses  of  the  hair  are :    i,  to  protect  from    sudden 
changes  of  temperature  ;    2,   to  serve  as  an    aid  to  the 
sense  of  touch;   3,    to  protect  sensitive  parts  from  dust,  - 
as  the  eyelashes,  and  the  hairs  in  the  nostrils  and  ears. 

The  nails  are  dense,  thick  plates  of  epidermis  growing 
from  a  number  of  papillae  situated  in  a  groove,  or  fold,  of 
the  skin  ;  there  are  a  number  of  fine  papillae  along  the 
bed  from  which  the  nail  grows  (Fig.  27).  Since  it 
grows  from  its  under  side  as  well  as  from  the  little  fold 
of  skin  at  its  root,  the  nail  is  thicker  at  the  end  than  near 


FIG.  26.  — SECTION  OF  HAIR  FOLLICLE, 
with  hair  in  center  surrounded  by  layers 
of  the  follicle.  Highly  magnified. 


22 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


FIG.  27. —  SECTION  OF  NAIL 
and  parts  beneath. 


the  root.     The  nail  moves  forward  as  it  grows.     It  moves 
its  whole  length  in  four  months,  hence  we  have  three  sets 

of  nails  each  year.  Make  a  mark 
on  a  nail  and  observe  the  number 
of  days  it  takes  to  move  a  certain 
distance.  If  not  pressed  back  at 
the  root,  the  skin  may  be  dragged 
along  by  the  nail  and  pulled  loose 
into  hangnails ;  if  the  skin  is 
pressed  back  too  much,  white  specks  or  flaws  appear  from 
imperfect  nutrition.  Attempt  to  pick  up  a  small  object 
without  using  the  nails. 

The  oil  glands  empty  into  the  hair  follicles  (see  Fig.  25). 
They  form  an  oil  from  the  blood  that  keeps  the  hair  glossy 
and  the  surface  of  the  skin  soft  and  flexible.  The  oil 
likewise  prevents  the  absorption  of  water.  In  the  palms 
and  soles,  where  there  are  no  oil  glands,  the  skin  may 
become  white  and  swollen  when  kept  long  in  water.  In 
some  places,  as  upon  the  nose  and  chin,  where  the  hairs 
are  very  small,  the  oil  glands  are^large 
and  may  be  said  to  open  directly  upon 
the  skin.  Such  oil  glands  may  become 
swollen  with  oil  and  dirt,  which  form 
what  are  called  black  heads.  Keeping 
the  face  clean  by  thorough  washing,  and 
stimulating  the  relaxed  glands  by  dashing 
cold  water  upon  the  face,  will  cure  this 
condition.  Hair  oil  should  never  be 
used  upon  the  hair,  as  the  oil  soon  be-  GLANDS 
comes  rancid,  and  besides  causes  dust  ducts> 
and  dirt  to  stick  to  the  hair.  The  use  of  hair  oil  and 
powdered  wigs  has  been  discontinued  along  with  many 
other  artificial  customs  common  a  century  ago. 


THE  SKIN 


FIG.  29. — PORES  on  ridges 
in  palm  of  hand. 


The  sweat  glands  (Fig.  28),  like  the  hair  bulbs,  are  deep 

in  the  lowest  part  of  the  dermis.     A  sweat  gland  has  the 

form  of  a  tube  coiled  into  a  ball ;  it  is 

connected   with   the  surface  by  the 

sweat  duct,  which  is  a  continuation 

of  this  tube  through  the  two  layers 

of  skin.      The  opening  of  the  tube 

upon    the    surface    is    called   a  pore 

(Fig.  29).    The  perspiration  is  formed 

in  the  coiled  part.     It  evaporates  as 

fast  as  it  flows  out  through  the  pores, 

if  the  secretion  is  slow ;  but  if  poured 

out   rapidly,    it    gathers   into    drops. 

The  perspiration  is  chiefly  water,  con- 
taining in  solution  several  salts,  including  common  salt 

and  a  trace  of  a  white,  crystalline  substance  called  urea. 

The  material  for  the 
perspiration  is  furnished 
by  the  blood  flowing 
around  the  gland  in  a 
network  of  fine  tubes 
(Fig.  30).  The  amount 
of  the  perspiration  is 
controlled  in  two  ways  : 

by  nerves   that  regulate 
FIG.  30.  —  COILED  TUBE  OF  SWEAT  GLAND, 

removed  from   network  of  capillaries  (c)    the    activity    of   the    epi- 
which  surrounded  it.  ^^    ^    ^.^    ^ 

gland,  and  by  nerves  that  regulate  the  size  of  the  blood 
vessels  supplying  the  gland. 

Experiment  4.  By  holding  a  piece  of  cold  glass  near 
the  hand,  or  by  placing  the  cheek  near  a  cold  window 
pane,  invisible  perspiration  may  sometimes  be  made 
visible. 


24  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

•^  1--  / 

THOUGHT  QUESTIONS.  —  Freckles,  Warts,  Moles,  Scars,  Proud 
Flesh,  Pimples,  Black  Heads.  By  applying  the  anatomical  facts  al- 
ready learned,  you  can  explain  the  above-named  peculiarities  sometimes 
found  on  the  skin.  A  rough  prominence  formed  by  several  papillae 
growing  through  the  epidermis  at  a  weak  spot  and  enlarging  is  called 
a  -  .  Small  patches  of  pigment  developing  on  the  hands  and  face 
from  much  exposure  to  the  sun  are  calledj—  -.'  The  growth  of  ex- 
posed dermis  sprouting  through  an  opening  in  the  epidermis  due  to 
accident  is  called  -  .  (This  should  be  scraped  off  and  cauterized  to 
aid  the  epidermis  to  grow  over  it  again.)  Sometimes  a  cut  heals  in  such 
a  way  that  no  epidermis,  and  therefore  no  pigment  cells,  cover  the  place 
of  injury,  which  is  occupied  only  by  white  fibrous  tissue  (cicatricial 
tissue)  of  the  true  skin.  In  this  case  the  mark  left  is  called  a  cicatrice 
or^ran^  If  pores  or  the  openings  of  oil  glands  become  clogged,  but 
not  enlarged,  little  swellings  called  -  may  result.  An  enlarged  pore 
filled  with  oil  and  dirt  is  called  a  -  .  A  spot  present  since  birth, 
dark  with  pigment,  and  often  containing  hairs  and  blood  vessels  is 
called  a 


Muscles  of  the  Skin.  —  The  capillaries  of  the  skin  are  so 
arranged  that  they  lie  between  bands  of  muscular  tissue. 
These  muscles  can  be  made  to  contract  and  compress  the 


FIG.  31.  — MUSCLES  ATTACHED  TO  HAIR  FOLLICLE.    (Diagram  by  Jegi.) 

A,  at  rest  and  hairs  in  usual  position;   B,  muscles  contracted  and  hairs  standing  on  end. 
Rising  of  the  hair  protects  beasts  from  cold,  but  "  goose  flesh  "  fails  to  protect  man. 

capillaries  in  such  a  way  as  almost  entirely  to  empty  them. 
What  is  the  position  of  the  muscles  which  cause  the  hair 
to  stand  on  end  in  cold  weather?  (Figs.  21,  31.)  These 
muscles  also  cause  goose  flesh  in  a  prolonged  cold  bath. 

Nerves   in    the  skin    are    of  several    kinds :    i,    nerves 
that  regulate  the  activity   of  gland  cells  ;   2,  nerves  that 


THE  SKIN 


give  the  sense  of  touch  and  pressure ;  3,  nerves  that  con- 
trol the  muscles  in  the  skin  ;  4,  nerves  that  give  the  feel- 
ing of  heat ;  5,  nerves  that  give  the  feeling  of  cold. 

Thermic  Nerves. — Although  cold  is  merely  the  absence 
of  heat,  there  are  two  kinds  of  temperature  nerves.  This 
can  be  proved  by  touching  the  skin  with  hot  and  cold 
needles.  Certain  small 
areas  of  the  skin  are 
found  sensitive  to  heat 
but  not  to  cold,  while 
with  other  areas  the  re- 
verse is  true.  The  skin 
is  more  sensitive  to  chill- 
ing than  to  heating.  An 
object  that  conducts  heat 
rapidly  feels  cooler  to 
the  skin  than  one  at  the  FIG.  32.  — SKETCH  OF  SKIN  for  blackboard 
same  temperature  that 

conducts  heat  slowly.  A  metal  or  stone  door  knob  feels 
cooler  than  the  door.  The  temperature  nerves  become 
fatigued  quickly.  Hence,  water  which  may  seem  painfully 
hot  or  cold  to  one  entering  a  bath  will  be  easily  borne 
after  a  few  seconds  have  passed. 

Experiments  5.  —  The  information  given  by  the  thermic, 
or  temperature,  nerves  is  relative.  An  object  is  felt  to  be 
cold  if  it  is  colder  than  another  object  which  has  just  been 
in  contact  with  the  skin  at  the  same  point.  On  this  prin- 
ciple, can  you  arrange  an  experiment  in  which  a  vessel  of 
water  will  feel  cold  to  one  hand  and  warm  to  another  at 
the  same  time  ?  6.  Draw  the  end  of  a  cold  (or  hot)  wire 
along  the  skin.  Does  it  feel  cold  all  the  time  ?  (Fig.  162.) 

Regulation  of  Temperature. —  As  is  well  known,  rapid 
running  or  violent  exercise  of  any  kind  causes  profuse  per- 


26  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

spiration.  What  is  the  connection  between  these  two 
occurrences  ?  Is  there  a  reason  why  one  always  follows  the 
other  ?  The  body  is  so  constructed  that  the  organs  work 
best  at  a  temperature  of  98.6°  Fahr.  If  its  temperature 
rises  a  little  above  98.6°,  the  body  cannot  do  its  work  well ; 
if  it  rises  much  above  or  falls  much  below  that  limit,  life 
may  be  in  danger.  Muscular  activity  is  carried  on  by  a 
kind  of  burning  process  which  would  raise  the  tempera- 
ture higher  than  98.6°  if  there  were  not  some  provision 
for  cooling  the  body.  The  sweat  glands  are  connected 
with  the  brain  by  means  of  nerves,  and  when  the  body 
has  too  much  heat  a  nerve  impulse  from  tJie  brain  causes 
the  sweat  glands  to  form  sweat  more  rapidly.  Heat  and 
exercise  may  cause  the  activity  of  the  sweat  glands  to 
increase  forty  times  the  usual  rate.  The  evaporation  of 
the  sweat  cools  the  body ;  for  a  large  amount  of  heat  is 
required  to  evaporate  a  small  amount  of  water.  This  is 
shown  by  the  cooling  effect  of  sprinkling  water  on  the 
floor  on  a  warm  day.  By  fanning,  we  hasten  the  cooling 
of  the  body. 

Exercise  causes  us  to  breathe  faster  and  causes  much  blood 
to  flow  through  the  skin.  Both  of  these  effects  aid  in  cooling 
the  body,  for  the  cool  air  is  drawn  into  the  lungs,  becomes 
warm,  and  takes  away  heat  when  it  leaves ;  and  the  warm 
blood  flowing  in  the  skin  loses  some  of  its  heat  to  the  air 
in  contact  with  the  skin.  The  more  blood  goes  to  the 
skin,  the  more  blood  is  cooled.  The  body  as  a  whole  may 
be  cooler,  but  we  feel  warmer  when  there  is  more  blood  in 
the  skin  because  of  the  effect  of  the  warm  blood  upon  the 
thermic  nerves.  There  are  no  thermic  nerves  except  in 
the  skin  and  mucous  membrane,  and  the  body  has  practi- 
cally no  sensation  of  heat  and  cold  except  from  the  skin  or 
mucous  membrane. 


THE  SKIN  2J 

Experiment  7.  A  moist  cloth  placed  on  the  bulb  of  a 
thermometer  will  cause  the  mercury  to  fall  several  degrees 
while  the  cloth  is  drying. 

Effects  of  Alcohol  upon  the  Skin. —  That  alcoholic  drinks 
make  the  skin  red  is  commonly  noticed.  Often  the  skin 
is  flushed  by  one  drink ;  the  blood-shot  eyes  and  purple 
nose  of  the  toper  are  the  results  of  habitual  use.  Can  you 
explain  why  alcohol  brings  a  deceptive  feeling  of  warmth  ? 
Why  does  alcohol  increase  the  danger  of  freezing  during 
exposure  in  very  cold  weather  ? 

THOUGHT  QUESTIONS.  — The  Functions  of  the  Skin.  1.  State  a 
fact  which  shows  that  the  skin  is  a  protection ;  gives  off  offensive  sub- 
stances ;  regulates  the  temperature.  2.  Is  it  more  necessary  for  men- 
tal workers  to  bathe  often  or  to  change  clothes  often  ?  Physical 
workers  ?  3.  Do  you  know  persons  who  scorch  their  hair  with  hot 
irons  ?  State  the  effect.  4.  What  is  lacking  in  the  skin  when  it  cracks 
or  chaps  ?  Why  does  this  occur  more  often  in  cold  weather  ? 

Effects  of  Indoor  and  Outdoor  Life.  —  The  plant  that  <-~ 
grows  out  of  doors  has  a  thick,  tough  bark,  strong  stems 
and  leaves.  It  can  survive  dry  winds,  hot  winds,  frost, 
hot  sun,  and  drought,  while  a  plant  of  the  same  species 
raised  in  a  hothouse  quickly  dies  if  exposed  to  unfavorable 
conditions.  Every  cell  and  fiber  of  the  outdoor  plant  has 
greater  vitality  and  more  resistance  than  the  house  plant. 
The  same  principle  applies  to  animals,  and  is  especially 
noticeable  in  human  beings.  Those  who  live  much  out  of 
doors,  exposed  to  sunlight  and  pure,  cold  air,  are  robust  and 
hardy ;  while  those  whose  occupations  keep  them  constantly 
indoors,  especially  if  no  physical  labor  is  necessary,  show 
by  their  pale  skins,  their  fat  and  flabby,  or  their  thin  and 
emaciated  bodies,  the  weakening  effect  of  such  a  life.  We 
are  descended  from  ancestors  that  lived  in  the  open  air, 
and  it  is  impossible  for  a  human  being  to  live  constantly 


28  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

indoors  without  degeneration  of  the  body  and  shortening 
of  life. 

A  Well-trained  Skin.  —  We  hear  a  great  deal  about 
training  the  muscles,  the  brain,  the  eye,  the  hand ;  yet 
we  may  fail  to  realize  that  the  skin  also  can  be  trained 
and  its  powers  developed,  or  it  can  be  allowed  to  become 
weak  and  powerless.  Soundness  of  the  skin  is  as  essential 
to  health  as  soundness  of  any  other  organ.  The  nineteen 
square  feet  of  skin  covering  the  body  contain  2,400,000 
sweat  glands.  It  is  plain  that  if  this  vast  secreting  surface 
is  so  weak  and  easily  affected  that  a  slight  draft  or  change 
in  the  weather  paralyzes  its  purifying  action,  the  body  is 
subject  to  many  maladies.  With  the  skin  in  a  healthy  con- 
dition, the  danger  of  taking  most  diseases  is  removed. 

Characteristics  of  a  Vigorous  Skin.  —  A  healthy  skin  is 
neither  hard  nor  flabby,  but  firm ;  it  is  not  dry,  dingy, 
rough,  or  sallow.  It  is  warm,  slightly  moist,  smooth,  supple 
and  elastic,  and  free  from  pimples  and  blotches.  It  per- 
spires freely  under  the  influence  of  exercise  or  heat,  and 
reddens  quickly  when  rubbed,  or  when  hot  or  cold  water 
is  applied  to  it.  A  person  who  readily  takes  cold,  who  is 
fearful  of  drafts  of  air  at  all  times,  probably  has  a  weak 
skin.  To  one  who  has  a  healthy  skin  drafts  are  danger- 
ous only  when  the  skin  is  moist  with  perspiration ;  cold 
drafts  may  then  do  harm.  Cold  air  and  cold  water  are 
the  best  means  of  toughening  a  tender  skin.  A  bath  is  to 
the  skin  what  gymnastic  exercise  is  to  the  muscles.  The 
muscle  fibers  in  the  walls  of  the  blood  vessels  and  the 
nerves  controlling  them  need  exercise  as  well  as  the  rest 
of  the  body.  Describe  a  lazy  skin. 

If  we  followed  the  outdoor  life  and  wore  the  scanty  cloth- 
ing of  savage  races,  the  rains,  the  cool  air,  and  the  sunligJit 
would  keep  our  skins  vigorous  and  sound.  But  inactivity 


THE  SKIN  29 

of  the  muscles  allows  the  sweat  glands  to  become  stopped 
up.  Thick  and  heavy  clothing  and  overheated  rooms  pre- 
vent the  nerves  from  being  stimulated  by  cold  air  and 
sunlight.  //  is  necessary  to  counteract  tJiese  weakening 
conditions  by  frequent  cold  bathing.  Even  the  lower  ani- 
mals bathe  :  birds,  dogs,  and  many  lower  animals  bathe  in 
the  rivers.  An  elephant  sometimes  takes  a  bath  by 
showering  water  over  his  back  with  his  trunk. 

THOUGHT  QUESTIONS.  —  The  Care  of  the  Skin.  1.  Why  does  the 
palm  of  a  washerwoman's  hand  absorb  more  water  than  the  back  of  the 
hand  ?  Why  should  a  painter  keep  his  hand  clean  ?  Why  do  dyed 
stockings  sometimes  cause  an  eruption  ?  2.  Why  is  linen  used  for 
towels  ?  3.  When  is  a  scar  incapable  of  being  affected  by  freckles  or 
tan  ?  4.  Why  can  a  scar  on  a  negro  be  white  ?  5.  How  may  rubber 
shoes  make  the  feet  moist  ?  6.  Why  does  the  heat  seem  more  oppres- 
sive in  moist  weather  ?  7.  Which  should  usually  wear  warmer  cloth- 
ing, a  farmer  or  a  merchant  ?  8.  Why  is  baldness  more  common 
among  men  than  among  women  ?  How  do  you  account  for  the  shape 
and  location  of  the  bald  spot  ?  9.  Why  should  we  remove  an  over- 
coat or  a  cloak  when  we  go  into  a  warm  room  ?  10.  Why  is  cold 
water  better  than  warm  water  for  the  daily  bath?  11.  Show  how  the 
wearing  away  of  the  outer  cells  of  the  epidermis  contributes  to  the 
cleanliness  of  the  body. 

Warm  Baths.  —  For  merely  cleansing  the  body,  warm 
water  is  more  effective  than  cold  water.  Any  one  who 
has  had  experience  in  washing  greasy  dishes  with  cold 
water  and  with  warm  water  knows  there  is  a  marked  dif- 
ference in  their  cleansing  power.  But  warm  baths  are 
relaxing,  and  are  best  had  just  before  retiring  to  prevent 
danger  of  taking  cold  after  the  bath.  If  taken  at  other 
times,  cold  water  should  be  dashed  upon  the  skin  at  the 
close  of  the  bath.  A  warm  bath  is  more  suitable  than  a 
cold  bath  for  one  who  is  greatly  fatigued.  A  bath  for 
cleanliness,  with  the  use  of  soap  and  tepid  water,  should 
be  taken  at  least  once  a  week  in  cold  weather,  and  oftener 


30  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

in  warm  weather.  Too  frequent  use  of  soap  or  warm 
water  makes  the  skin  thin  and  hard  and  dry. 

Cold  Baths.  —  A  daily  cold  or  cool  bath,  although  it  aids 
in  keeping  the  skin  clean,  has  for  its  chief  purpose  the 
invigoration  of  the  skin  and  the  training  of  it  to  prompt 
reaction  to  cold.  The  whole  body  reacts  also.  The  nervous 
system  is  toned  up,  the  lungs  draw  deep  breaths,  the  appe- 
tite is  improved,  the  heart  and  all  internal  organs  take  on 
renewed  activity.  The  cold  bath  replaces  the  cool  breezes 
that  constantly  stimulated  the  skins  of  our  remote  savage 
forefathers.  Such  a  stimulus  is  natural,  and  is  followed 
by  no  evil  effects,  such  as  follow  the  artificial  excitement 
from  drinking  alcoholic  liquors. 

When  cold  water  is  applied  to  the  skin,  there  is  a  sudden 
contraction  of  the  blood  vessels.  This  is  followed  by  a  dila- 
tion of  the  blood  vessels  and  a  return  of  blood  to  the  skin, 
which  causes  a  glow.  This  is  called  a  reaction.  A  cold 
bath  should  always  be  short,  as  a  long  cold  bath  may  chill 
the  body  too  much.  If  the  feet  and  hands  continue  cold 
after  the  bath,  or  if  the  head  aches,  this  shows  that  the 
person  remained  in  the  bath  until  after  the  reaction  was 
finished,  and  the  body  had  been  chilled  a  second  time.  A 
short  cold  bath,  not  more  than  one  or  two  minutes  in 
length,  followed  by  vigorous  rubbing  until  a  good  circula- 
tion is  established,  is  good,  even  for  a  delicate  person. 
Gradually  the  ability  to  react  improves,  until  colder  water 
and  longer  baths  may  be  used.  In  the  case  of  very  deli- 
cate persons,  the  arms  only  may  be  sponged  with  cold 
water  at  first,  and  the  area  to  which  the  cold  water  is 
applied  may  be  extended  little  by  little  at  each  successive 
bath  for  a  week.  Persons  who  easily  take  cold  especially 
need  the  training  of  the  skin  that  results  from  cold  baths. 
Muscular  exercise  also  strengthens  the  circulation.  But 


THE  SKIN  31 

it  is  almost  impossible  to  lead  persons  with  weak  and 
degenerate  skins,  who  shudder  at  the  thought  of  a  draft, 
to  see  the  error  of  their  ways.  If  they  would  never  have 
to  expose  themselves  to  cold,  they  might  safely  indulge  in 
their  love  of  high  temperature,  but  frequent  exposure  is 
inevitable,  and  such  persons  have  worse  colds  and  have 
them  oftener  than  people  who  do  not  pet  and  coddle  their 
nerves  of  temperature.  The  weaker  the  skin  becomes,  the 
more  it  needs  training,  but  the  more  they  overheat  it 
instead.  Remaining  in  an  overheated,  unventilated  room 
more  quickly  brings  on  a  cold  than  chilling  the  body. 

The  materials  of  which  clothing  is  made  are  linen,  cotton, 
silk,  wool,  leather  and  fur,  and  rubber  for  waterproof  cloth- 
ing. Clothing  does  not  give  heat  to  the  body,  but  keeps 
the  body  from  losing  too  rapidly  the  heat  generated  by  the 
vital  processes.  Loosely  woven  clothing  contains  air  spaces 
and  does  not  conduct  heat  away  from  the  body  as  fast  as 
tightly  woven  or  tight-fitting  clothing.  If  the  body  is 
properly  clothed,  the  temperature  of  the  air  between  the 
clothes  and  the  body  will  be  seventy-five  to  eighty-five 
degrees,  even  in  freezing  weather.  Two  things  must  be 
considered  in  deciding  the  use  of  fabrics  for  clothing  :  first, 
whether  they  conduct  heat  rapidly  or  slowly ;  second,  whether 
they  absorb  and  transmit  moisture  rapidly  or  slowly.  Be- 
cause woolen  conducts  heat  slowly,  it  is  usually  believed 
to  be  the  best  material  for  winter  wear  ;  but  woolen  absorbs 
and  gives  up  moisture  very  slowly ;  and  if  sensible  perspira- 
tion forms,  it  is  kept  in  as  a  kind  of  sheet  of  moisture 
covering  the  body,  and  conducts  away  the  heat  rapidly. 
Linen  and  cotton  absorb  moisture  readily  and  transmit  it 
rapidly,  so  that  these  fabrics  keep  the  body  dry. 

Experiments.  —  8.  Sprinkle  water  upon  a  woolen  and  a 
cotton  cloth.  Which  absorbs  more  water?  9.  Immerse 


32  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

the  cloths  in  water  and  hang  them  up  to  dry.  Which 
becomes  dry  first  ? 

Clothing  and  Climate.  —  Many  physiologists  now  hold 
that  cotton  and  linen  are  best  for  underwear,  as  they  keep 
the  skin  dry  by  rapid  absorption  and  evaporation.  But  in 
order  that  the  evaporation  may  not  be  so  rapid  as  to  chill 
the  body,  woolen  should  be  worn  for  outer  clothing  in  cold 
climates ;  it  is  also  better  suited  for  underwear  in  climate 
and  weather  so  severe  that  there  is  little  risk  of  sensible 
perspiration  forming.  Why  should  people  with  a  tendency 
to  perspire  freely  avoid  woolen  underclothing? 

White  or  light  colors  for  clothing  are  best  in  warm  cli- 
mates and  in  summer,  as  they  reflect  heat  and  light,  while 
dark  colored  materials  absorb  them.  White  clothing  trans- 
mits unchanged  to  the  body  any  light  that  may  penetrate 
between  its  threads,  while  dark  outer  clothing  changes  sun- 
light to  heat,  which  does  not  affect  the  skin  so  favorably 
as  light. 

People  who  go  to  different  climates  should  change  their 
dress  with  the  climate.  Englishmen  who  go  to  India, 
Americans  who  go  to  the  Philippines  or  to  Alaska,  people 
making  trips  between  the  Gulf  states  and  the  Northern 
states,  realize  this  need.  Yet  there  have  been  absurd  in- 
stances of  disregard  of  this  rule  of  health.  People  from 
northern  Europe  sometimes  bring  with  them  feather  beds 
to  sleep  under  in  the  warmer  portions  of  the  United  States 
and  continue  to  use  them. 

Clothing  and  Weather. — The  old  rules  requiring  winter 
underclothing  to  be  put  off  and  resumed  at  certain  dates, 
were  made  in  a  time  when  the  science  of  hygiene  was  un- 
known, and  people  had  no  adequate  idea  of  the  complexity 
of  the  body.  As  an  instance  of  the  working  of  such  rules, 
a  grandmother  required  a  girl  for  years  to  wear  winter 


THE  SKIN  33 

flannels  until  a  certain  date ;  the  girl  always  had  very  bad 
colds  in  the  spring.  She  afterward  disregarded  the  rule, 
acted  in  accordance  with  her  feelings,  and  seldom  had  a 
cold.  If  the  spring  happens  to  be  unusually  early,  there 
is  no  reason  why  a  farmer  should  swelter  in  thick  clothing 
because  such  clothes  were  comfortable  at  that  date  last  year. 
Comfort  is  a  guide  to  the  health.  The  science  of  hygiene 
contains  no  mechanical  rules,  but  teaches  that  observation, 
reason,  and  adaptation  to  climate,  season,  and  individual 
needs  must  be  the  basis  of  hygienic  conduct.  On  the  con- 
trary, the  complexity  of  this  science  warns  us  against 
the  inflexible  rules  by  which  people  with  indolent  minds 
or  exact,  mechanical  ways  of  thinking  govern  their 
conduct. 

Babies  and  young  children  cannot  always  make  their 
wants  known  in  an  unmistakable  way.  Many  young  chil- 
dren die  every  year  from  lung  or  bowel  troubles  brought 
on  by  insufficient  clothing  or  bed  covering.  This  may  occur 
in  summer  because  the  first  part  of  the  night  is  warm  and 
the  covering  is  not  enough  to  protect  the  body  later  against 
the  cold.  Which  cools  more  quickly  when  hot,  a  small 
pebble  or  a  large  stone  ?  The  one  which  has  the  greater 
cooling  surface,  in  proportion  to  its  size,  cools  more  quickly. 
Thus  we  see  why  infants  suffer  more  from  exposure  than 
adults.  As  food  is  the  source  of  the  bodily  heat  (which 
clothing  only  serves  to  retain),  babies  must  be  fed  more 
often  than  adults. 

EXERCISES  IN  WRITING.  —  Sunshine.  Fashion  and  Health.  Simon 
says  Wig-wag.  Tight  Shoes.  Health  and  Country  Life.  The  Face 
and  what  it  Betokens.  Artificial  Complexions :  how  they  are  put  on. 
Natural  and  Artificial  Beauty.  The  Drunkard's  Home  and  Life  therein. 
Two  Ways  of  Spending  an  Evening.  Exposure  and  Coddling  (see 
also  page  120). 


34  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

PRACTICAL  QUESTIONS.  —  Is  cotton  or  woolen  clothing  more  liable  tc 
shrink  out  of  shape  and  size  ?  To  make  the  skin  clammy  with  mois- 
ture ?  To  catch  fire  ?  To  cost  more  ?  To  be  eaten  by  moths  ?  Is 
linen  more  like  cotton  or  woolen  in  its  effects  ? 

Oral  Review  (by  the  Competitive  Method). — These  questions  require 
merely  "  yes  "  or  "  no  "  for  an  answer.  The  teacher  can  make  similar 
questions  for  the  other  chapters.  An  oral  review  should  be  given 
at  the  end  of  each  chapter.  The  teacher  states  the  question,  pauses 
awhile  for  pupils  to  think,  and  says  "  hands  up."  Those  who  wish  to 
answer  "  yes  "  will  raise  their  hands.  If  they  are  wrong,  they  will  go  to 
the  rear  of  the  room,  or  be  seated  if  the  class  is  standing  in  line.  If 
those  who  failed  to  raise  the  hands  are  wrong,  they  leave  the  line. 
When  only  one  fifth  of  the  class  are  left  in  the  contest,  their  names  are 
recorded,  and  the  whole  class  take  their  places  for  another  trial. 

Are  there  any  fibers  in  the  epidermis  ?  Do  all  the  cells  of  the  epi- 
dermis have  nuclei  ?  (Fig.  23.)  Are  all  of  the  cells  of  the  epidermis 
flattened  ?  Is  the  pigment  in  the  cells  ?  Between  them  ?  Are  all 
cells  colored  ?  Do  the  oil  glands  usually  open  directly  on  the  surface 
of  the  skin  ?  Is  an  oil  gland  like  a  bag  ?  Like  a  tube  ?  (Same  questions 
for  sweat  glands.)  Is  the  skin  on  any  portion  of  the  body  without  oil 
glands  ?  Are  the  papillae  arranged  in  lines  in  any  part  of  the  skin  ?  If 
several  papillae  grow  through  a  weak  spot  in  the  epidermis  and  form  a 
rough  prominence,  is  it  called  a  freckle?  A  pimple?  A  wart?  Is  there 
only  one  kind  of  temperature  nerves?  Are  there  two  kinds?  Raise 
your  hands  at  the  name  of  each  of  the  following  qualities  that  belong  to 
a  healthy  skin :  flabby,  elastic,  pimply,  rough,  smooth,  warm,  pink,  sal- 
low. Does  soft,  loosely  woven  clothing  keep  the  heat  in  the  body  bet- 
ter than  tightly  woven  clothing  ?  Does  woolen  absorb  moisture  faster 
than  cotton  ?  Does  woolen  give  off  moisture  as  fast  as  cotton  ?  Does 
the  dermis  have  more  of  blood  vessels  than  of  anything  else  ?  Of  nerves  ? 
Of  connective  tissue  ?  Are  there  any  blood  vessels  in  the  epidermis  ? 
Does  perspiration  take  any  solids  away  from  the  skin  when  it  evapo- 
rates ?  Is  heat  more  oppressive  in  dry  weather  ?  Wet  weather  ?  Is 
perspiration  more  abundant  in  damp  weather  ?  Is  visible  perspiration 
more  abundant  then  ?  Does  an  abundance  of  permanent  wrinkles 
show  that  the  body  is  too  small  for  the  skin?  Too  large?  Can  the 
mucous  membrane  do  part  of  the  skin's  work  for  it  ?  Does  the  name 
of  the  pit  in  which  the  hair  grows  I  egin  with  g, — rt — h,  — 0,  — /"? 


C35) 


MASAI  BONE&-" 


THE  CRANIUM. 

•MALAR  (CH  EEK)  BONE  . 
-SUPERIOR  MAXILLARY  BONES 
INFERIOR  MAXILLARY  BONE 

SPINAL  COLUMN.  CERVICAL  REGION. 


(SCAPULA) 
4HOUICE.R  BLADE  — 


SPINAL  COLUMN 
U INNOMINATE  90N6 


PLATE  I.      FIG.  33. —  THE  SKELETON. 

Stale  the  scientific  (Latin)  name  of  the  following  bones:  skull,  cheek  bone,  upper 
and  lower  jawbones;  collar  bone,  shoulder  blade,  breastbone;  bones  of  upper 
arm,  lower  arm,  wrist,  palm,  fingers;  hip,  thigh,  kneecap,  shin  bone,  splint 
bone ;  bones  of  ankle,  instep,  toes. 


CHAPTER   III 

THE  SKELETON 

Observational  Study  of  Hand  and  Arm  (Fig.  33).  —  By 

touch  and  sight  we  find  that  each  finger  has  bones, 

and  that  the  thumb  has  -  — ,  making  in  all  for  one 

hand.  There  are  bones  in  the  palm  of  the  hand. 

The  palm  bones  of  the  -  -  are  bound  firmly  together,  but 
the  palm  bone  of  the  -  -  is  free  to  move  in  any  direction. 

Thus  the may  be  brought  opposite  to  each  of  the . 

Attempt  to  pick  up  and  handle  objects  without  using  the 
thumb.  What  is  the  result  ?  The  palm  bones  cannot  be 
traced  through  their  whole  length  by  feeling  them,  since 
in  the  upper  half  of  the  palm  the  flesh  is  very  thick. 

Is  the  division  between  the  palm  and  the  wrist  equally 
plain  on  the  palm  side  of  the  hand  and  the  back  of  the 
hand  ?  The  wrist  bones  are  nearly  cubical,  and  are  arranged 
in  two  rows.  Rapidly  bend  and  straighten  the  fingers  of 
one  hand,  and  with  the  fingers  of  the  other  hand  find 
whether  you  can  feel  a  firm  cord  crossing  each  knuckle  and 
running  toward  the  wrist  (Fig.  34).  When  the  cords  are 
tightest,  the  fingers  are  bent  backward.  Can  you  see  the 
cord  rise  as  you  work  the  fingers  ?  There  are  cords  on 
the  palm  side  to  bend  the  fingers;  but  because  of  the  thick 
skin  in  the  palm,  it  is  more  difficult  to  see  their  position. 
However,  in  the  wrist  at  the  base  of  the  palm,  you  can  feel 
two  hard  wrist  bones  that  confine  the  cords  in  the  softer 
space  between  them.  You  may  also  observe  the  cords 

36 


THE  SKELETON 


37 


Muscle 


moving  on  the  palm  side  of  the  wrist  when  the  fingers  are 

moved  (Fig.  34).     We  have  seen  that  the 

fingers  are  moved  backward  and  forward 

by  tightening  first  one  set  of  these  cords, 

and   then   the   other.      These   cords  are 

called  tendons.     One  end  of  each  tendon 

is  attached  to  a  bone  and  the  other  end 

is  attached  to  a  muscle.     It  is  plain  that 

the   muscles   that  move  the  fingers  are 

somewhere   above   the   wrist.      Can  you 

locate  them   by  feeling  them  while  you 

move  the  fingers  ?      (A  muscle  shortens, 

thickens,    and  hardens  when  it  moves  a 

bone.) 

In  how  many 
directions  do  the 
joints  between  the 
fingers  and  palm  al- 
low the  fingers  to 
move  ?  Each  finger 
has  two  joints  be- 
tween its  three 
bones.  In  how  many  directions 
does  each  of  these  joints  allow  mo- 
tion  ?  Does  the  wrist  joint  allow 
more  freedom  of  motion  back  and 
forth,  or  from  side  to  side  ? 

Rest  the  elbow  on  the  table,  keep 
the  wrist  straight,  and  try  whether 

FIG.  35.  — BONES  of  right  fore-  the  hand  will  rotate.    What  fraction 

of   a   complete   rotation   does   the 

A,  palm;  B,  back  of  hand.  t 

hand   make  ?     To  understand   the 
rotation,  study  Figure  35.      You  will  see  that  there  are 


Tendon 


FIG.  34.  —  MUS- 
CLES AND  TEN- 
DONS of  forearm. 


38  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

two  bones  in  the  forearm..  The  ends  of  these  bones  may 
be  felt  immediately  back  of  the  wrist  joint  as  bumps  under 
the  skin.  The  larger  bump,  or  knob,  is  on  the  little  finger 
side  of  the  arm.  The  first  bone  of  the  forearm  is  attached 
to  the  elbow  and  the  second  bone  lies  by  the  side  of  it,  and 
is  bound  to  it  near  the  elbow  (see  Fig.  45).  The  second 
bone  turns  around  the  first,  and  the  hand,  being  attached 
to  this  bone,  turns  with  it  (Fig.  35). 

Bend  the  right  elbow  and  at  the  same  time  feel  the 
upper  arm  with  the  left  hand.  The  large  muscle  that  can 
be  felt  to  swell  and  harden  is  called  the  biceps.  Repeat 
the  movement,  but  clasp  the  elbow  instead  of  the  upper 
arm.  Do  you  feel  a  large  tendon  that  goes  from  the  biceps 
to  the  forearm?  (Fig.  55.)  Straighten  the  arm  and  at 
the  same  time  feel  the  side  of  the  upper  arm  opposite  to 
the  biceps.  Do  you  feel  a  large  muscle  that  is  contract- 
ing ?  You  can  perhaps  feel  that  there  is  a  single  bone 
between  the  shoulder  and  elbow,  and  that  it  is  round  and 
smooth  (Fig.  33).  We  find  that  to  bend  a  joint  the  mus- 
cle on  one  side  of  the  arm  contracts,  and  to  straighten 
it  a  muscle  on  the  other  side  contracts. 

Review  of  Bony  Tissue. — Where  are  the  bone  cells? 
How  does  nourishment  reach  them  ?  How  has  the  min- 
eral part  of  the  bones  been  deposited  ?  How  long  may 
bone  cells  live  ? 

Need  of  the  Body  for  a  Framework.  —  The  jellyfish  and 
a  few  other  animals  in  the  sea  are  soft  throughout. 
The  slug  and  a  few  other  land  animals  have  no  hard  or 
stiff  parts.  An  animal  without  hard  parts  cannot  stand 
erect,  and  must  move  slowly  and  with  difficulty.  The 
human  body  without  its  skeleton  would  lack  its  beautiful 
proportions,  its  graceful  motions,  and  dignified  bearing. 
There  are  two  kinds  of  skeletons  among  animals :  the 


THE  SKELETON 


39 


Compact 
or  dense 
tissua. 


outside skeletons  (examples  :  the  crawfish,  the  grasshopper); 
the  inside  skeletons  (examples :  fish,  birds,  and  beasts). 
The  inside  skeleton  allows  more  freedom 
of  motion  and  is  by  far  the  better  kind. 
Forms  and  Uses  of  Bones.  — The  three 
chief  uses  of  bones  aw~fmrtectwn,  mojii&, 
twd-fttftwrt.  In  order  to  fulfill  these 

purposes,  the  bones  must 
•A  have  different  sizes, 

shapes,    and     positions. 

The  bones   are   classed 

by  shape,  as  long,  fiat, 

and  irregular.       Those 

whose    chief    use   is    to 

protect   are    broad   and 

flat.     The  bones  which 

furnish  support  are  thick 
"*•  C      and   solid;     those     de- 
signed to  aid  in  motion 

are   long    and   straigJit. 

There  are  two  hundred 

and   six    bones    in    the 

adult  skeleton,  if  we  in- 
clude six  small  bones  in 

the  ear.  FIG.  36.  —  FEMUR,  sawed 

Structure  of  Bones.  —     !?"*hwi*-    T,he  re<! 

blood  cells  are  formed 

The    Structure  Of  a  long        in  the  red  marrow  of 
i  ,  .      _,.  the  spongy  part. 

bone  is  shown  in  Figure 

FIG    f  —FRONT   ^'      ^   kaS  a  ^on&'  hollow  shaft  of  hard, 

VIEW  OF  LEFT  compact  bone,  and  enlarged  ends  composed 

of  spongy  bone.     The  hollow  in  the  shaft 

is  filled  with  yellow  marrow,  which  is  composed  of  blood 

vessels  and  fat,  and  aids  in  nourishing   the  bone.     The 


40  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

long  bones  are  found  in  the  limbs  (Fig.  33).  The  flat 
bones  and  irregular  bones  are  spongy  inside,  and  hard  and 
compact  near  the  surface.  For  instance,  in  the  skull  the 
outer  and  inner  surfaces  form  two  armorlike  plates,  and 
the  spongy  layer  between  them  lessens  the  jar  to  the  brain 
from  a  blow  upon  the  head.  There  is  a  red  marrow  in 
the  cavities  in  the  spongy  parts  of  bones  (Fig.  36).  The 
red  blood  cells  are  formed  in  this  marroiv.  The  bones  have 
a  close-clinging,  fibrous  covering  composed  of  connective 
tissue  and  blood  vessels.  It  is  called  the  periosteum. 

Composition  of  Bone.  — Experiment  10.  Place  a  bone  in  a 
hot  fire  and  let  it  remain  for  three  or  four  hours.  It  will 
keep  its  shape  however  long  you  burn  it ;  but  unless  you 
handle  it  carefully  when  you  take  it  out,  it  will  crumble  to 
pieces.  If  not  thoroughly  burned,  the  bone  will  be  black 
from  the  carbon  of  the  animal  matter  still  left  in  it. 

Experiment  u.  Obtain  a  slender  bone  like  the  rib  of  a 
hog  or  the  leg  bone  of  a  fowl,  and  put  it  into  a  vessel 
containing  strong  vinegar  or  two  ounces  of  muriatic  acid 
and  a  pint  of  water.  Leave  it  there  for  four  days.  When 
the  bone  is  taken  out,  it  will  be  so  soft  that  it  can  be  tied 
into  a  knot.  The  acid  may  be  washed  off,  and  the  bone 
preserved  in  a  bottle  of  alcohol  or  glycerine. 

These  experiments  show  that  the  bones  contain  a  min- 
eral or  earthy  substance,  which  makes  them  hard  and  stiff, 
and  a  certain  amount  of  animal  matter,  called  gelatine, 
which  binds  the  mineral  matter  together  and  makes  the 
bones  tough  and  somewhat  elastic.  The  fire  burned  out 
the  animal  matter  of  the  first  bone,  and  the  acid  dissolved 
out  the  mineral  matter  of  the  second  bone.  The  mineral 
matter  is  chiefly  lime,  and  makes  up  about  two  thirds  of  the 
weight  of  the  bone.  The  animal  gelatine  is  a  gristly  sub- 
stance. As  the  body  grows  old,  the  animal  matter  of  the 


THE  SKELETON 


bones  decreases,  and  they  become  lighter.    They  are  more 

easily  broken  and  do  not 

heal  so  readily  as  the  bones 

of  young  persons. 
The  skeleton  is  subdivided 

into  the  bones  of  the  head, 

trunk,    and    limbs.       The 

bones  of  the  trunk  consist 

of    the   spine   and   of   the 

chest,  the  shoulder  blades, 

collar  bone,  tongue  bone, 

and  hip  bones. 
The  spinal  or  vertebral 

column    is     made    up     of 

twenty-six  bones  (Figs.  38, 

39).     It  is  the  axis  of  the 

human  skeleton  to  which 

all  other  bones  are  directly 

or  indirectly  attached.    All 

animals  with  inside  skele- 
tons have  this  column, 

and  are  called  vertebrates. 

Fish,  reptiles,  birds,  beasts, 

apes,  and  man  are  verte- 
brates. The  spine,  as  this 

column  is  sometimes  called, 

is  not  only  the  main  con- 
necting structure  and  sup- 
port of  the  body,  but  it 

forms   a   channel   through 

which    passes    the    spinal 

cord.     Figure  40  shows  a  vertebra,  or  one  of  the  bones 
that  compose  the  column.     The  projecting  points  are  for 


FIG.  38. —VERTE- 
BRAL COLUMN. 
Rear  view. 


FIG.  39.  —  VERTE- 
BRAL COLUMN. 
Side  view. 


42  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

the  attachment  of  ligaments  and  muscles.  The  main 
body  of  each  vertebra  is  for  supporting  the  weight  trans- 
mitted by  the  column  above.  Just  behind  this  thick  body 
is  a  half  ring  (Fig.  40),  which,  with  the 
half  rings  on  the  other  vertebrae,  form 
the  canal  for  the  spinal  cord.  Between 
the  vertebrae  are  thick  pads  of  gristle,  or 
cartilage,  which  act  as  cushions  to  prevent 
jars,  and  by  compression  allow  bending 
of  the  spinal  column  in  all  directions. 

The  Chest  (see  Fig.  97).  —  The  twelve 
pairs  of  ribs  are  attached  to  the  spinal 
column  behind,  and  extend  around  toward 

the  front  of  the  body,  somewhat  like  hoops. 
FIG.  40.  —  SIDE  AND 

UNDER  VIEW  OF  A  The  first  seven  pairs,  called  true  ribs, 
are  attached  directly  to  the  breastbone. 
Each  of  the  next  three  pairs,  called  false  ribs,  are  attached 
to  the  pair  above  it.  The  last  two  pairs,  called  floating- 
ribs,  are  free  in  front. 

The  tongue  bone  (see  colored  FIG.  91)  is  readily  felt 
in  the  neck.  Many  muscles  are  attached  to  it,  the  chief 
one  being  the  tongue.  This  bone  is  one  of  the  few  bones 
in  the  body  that  is  not  attached  to  any  other  bone.  It  is 
shaped  like  the  capital  letter  U,  is  felt  to  be  somewhat 
rough,  and  can  be  moved  from  side  to  side  with  the  hand. 

The  collar  bones  (Fig.  33)  can  be  traced  from  the 
shoulders  until  they  nearly  meet  on  the  breastbone  at  the 
top  of  the  chest.  The  collar  bone  is  shaped  like  the  Italic 
letter/*,  and  serves  to  hold  the  shoulder  out  from  the  chest 
that  the  motions  of  the  arm  may  be  free. 

The  flat,  triangular  shoulder  blade  (Fig.  41)  can  be  felt 
by  reaching  with  the  right  hand  over  the  left  shoulder. 
It  spreads  over  the  ribs  like  a  fan.  Its  edges  can  be  made 


THE  SKELETON 


43 


out,  especially  if  the  shoulder  is  moved  while  it  is  being 
felt.  The  high  ridge  which  runs  across  the  bone  can  be 
felt  extending  to  the  top  of  the 
shoulder. 

The  edges  of  the  hip  bones  can 
be'felt  at  the  sides  of  the  hips  (Fig. 
42).  The  hip  bones,  with  the  base 

of  the  spine,  form  a  kind  of  basin 

FIG.  41.— 

called  the  pelvis.  LEFT  SHOULDER 

The  skull  (Fig.  43)  rocks,  or  nods,  £££"• 
on  the  top  vertebra.     It  consists  of 

the  cranium,  or  brain  case,  and  the  bones  of  the  face.  The 
shapes  and  names  of  the  bones  of  the  skull  are  shown  in 
Figure  43.  The  cranium  appears  to  the  touch  to  be 
smooth  and  round,  with  no  sign  of  the  joints  that  unite 


FIG.  42.— JOINTS  OF  PELVIS,  seen  from  the  front. 


Capsule 
of  hip- 
joint 


Capsule  of  hip  jbint  was  cut  at  i ;  the  round  ligament, 
a  cord  connecting  socket  with  middle  of  ball,  is 
seen  at  2.  Other  lines  mark  other  ligaments. 

its  eight  bones.  Most  of  the  bones  of  the  face  can  be 
traced  by  feeling  them.  The  lower  jawbone  is  distinct; 
the  two  upper  jawbones  meet  just  beneath  the  nose; 


44 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


the  cheek  bones  stand  out  prominently  in  the  cheeks.     The 
two  narrow  nasal  bones  form  the  ridge  of  the  nose  for 

half  its  length,  the 
lower  part  of  its 
ridge  being  carti- 
lage ;  for  the  nose 
is  so  prominent 
that  if  it  were  not 
flexible  it  would 
often  be  broken. 

The  arms  and 
legs  have  bones 
that  closely  corre- 
spond to  each  other. 
The  Latin  names 
of  these  bones,  as 
well  as  of  all  the 
other  bones,  are 
given  in  Figure  33. 
There  are  30  bones  in  each  arm  and  30  in  each  leg.  Here 
is  a  list  of  the  bones  of  the  arm,  followed  by  the  names  in 
brackets  of  the  corresponding  leg  bones :  upper  arm  bone 
[thigh  bone],  2  forearm  bones  [shin  bone  and  splint  bone], 
8  wrist  bones  [7  ankle  bones],  5  palm  bones  [5  bones  of 
-instep],  14  finger  bones  [14  toe  bones].  The  shin  bone 
is  the  larger  bone  between  knee  and  ankle,  Its  lower  end 
can  be  felt  as  a  bump  at  the  ankle.  The  long,  slender 
splint  bone  and  the  shin  bone  are  bound  side  by  side. 

Differences  between  Arm  and  Leg.  —  There  is  a  saucer- 
like  bone,  called  the  kneecap,  embedded  in  the  large  liga- 
ment which  passes  over  each  knee.  There  is  no  such 
bone  in  the  elbow.  There  is  one  less  bone  in  the  ankle 
than  in  the  wrist,  hence  there  are  the  same  number  of 


FIG.  43.  — SIDE  VIEW  OF  SKULL. 

The  bones  of  the  cranium,  or  brain  case,  are  broad  and  flat; 
the  bones  of  the  face  are  irregular,     th,  hyoid  bone. 


THE  SKELETON  45 

bones  in  the  arm  and  leg.  The  shoulder  joint  is  more 
freely  movable  than  the  hip  joint.  The  fingers  are  longer 
and  more  movable  than  the  toes  ;  the  thumb  moves  far 
more  freely  than  the  big  toe.  The  instep  is  much  stronger 
than  the  palm  ;  for  each  instep  must  support,  unaided,  the 
weight  of  the  whole  body  at  each  step,  with  any  other 
weight  that  the  person  may  be  carrying.  The  palm  is 
nearly  flat,  but  the  instep  is  arched  to  prevent  jars  (Fig. 
47).  When  the  weight  of  the  body  is  thrown  on  the  foot 
at  each  step,  the  top  of  the  arch  is  pressed  downward, 
making  the  foot  longer  than  before.  The  arch  springs  up 
when  the  weight  is  removed. 

THOUGHT  QUESTIONS. —The  Shapes  of  Bones.  Write  Z,  F,  or  / 
after  these  names  (see  Figs.  36,  47),  according  as  the  bones  are  long, 
flat,  or  irregular :  face,  skull,  vertebra,  hip,  rib,  breast- 
bone, collar  bone,  shoulder  blade,  upper  arm  bone,  lower 
arm  bones,  wrist,  palm,  fingers,  thigh  bone,  shin  bone, 
splint  bone,  ankle,  instep,  toes,  kneecap,  tongue  bone. 

Joints.  —  The  meeting  of  two  bones  forms  a  joint. 
Some  of  the  joints  are  immovable.  The  skull  bones  join 
in  zigzag  lines  called  sutures,  formed  by 
the  interlocking  of  sawlike  projections 
(Fig.  44).  These  immovable  joints  are 
necessary  for  the  protection  of  the  brain, 
which  is  the  most  delicate  of  the  organs. 
The  brain  attains  almost  its  full  size  by 
the  seventh  year  of  life,  and  its  bony  case 
need  grow  very  little  after  that.  The  joints 
of  the  pelvis  are  also  immovable.  All  FIG.  44.— SUTURES 
movable  joints  have  two  cartilages,  and 
as  the  bones  turn,  one  cartilage  slips  over  the  other. 
There  is  an  intermediate  class  of  joints  found  between  the 
vertebrae  and  where  the  ribs  join  the  breastbone.  These 


46 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


joints  depend  for  their  motion  upon  the  flexibility  and 
compressibility  of  their  cartilages.  They  are  called 
mixed,  or  elastic,  joints,  and  allow  slight 
motion.  Such  a  joint  has  only  one  cartilage. 
Kinds  of  Movable  Joints.  —  The  movable 
joints  are  found  chiefly  in  the  limbs. 
When  one  end  of  the  bone  is  rounded  and 
fits  into  a  cuplike  hollow,  the  joint  allows 
motion  in  all  directions,  and  is  known  as 
a  ball-and-socket  joint.  The  hip  joints  and 
shoulder  joints  are  examples.  A  Jiinge  joint 
allows  motion  in  only  two  (opposite)  direc- 
tions ;  for  example,  the  to-and-fro  motion 
of  the  elbow.  A  pivot  joint  allows  a  rotary 
motion  (Figs.  35,  45).  A  gliding  joint  con- 
sists of  several  small  bones  sliding  one  over 
another  ;  examples,  wrists  and  ankles. 
Why  the  Long  Bones  are  enlarged  at  the 

FIG.  45.  -  BONES    joints.  —  You  learned  that  the  ends  of  the 

OF  FOREARM. 
A  ligament  holds  the    long  bones    are 


enlarged,  and  of 
rotates.  spongy    structure. 

This  structure  adds  to  the  elasticity 
of  -the  bone  and  lessens  jars.  The 
enlargement  at  the  joints,  by  rais- 
ing the  tendons  away  from  the 
limb,  brings  them  at  an  angle  to 
the  bone,  and  thus  gives  them 
more  effect  in  bending  the  limb 
than  they  would  have  if  parallel 
to  the  bone.  When  a  fisherman 
wishes  to  lift  his  rod,  he  does  not  pull  toward  the  end  of 
the  rod,  but  at  an  angle  to  the  rod. 


FIG.  46.  —  DIAGRAM  OF  A  JOINT. 


THE  SKELETON  4; 

The  Four  Features  presented  by  a  Movable  Joint  (Fig. 
46).  —  If  not  held  in  place,  the  bones  would  slip  out  of 
their  sockets,  hence  there  are  ligaments,  or  tough  bands,  to 
bind  the  bones  together.  Sudden  jolts  would  jar  the 
bones  and  injure  them  ;  shocks  are  prevented  by  a  layer 
of  elastic  cartilage  over  the  end  of  each  bone.  The  mov- 
ing of  one  bone  over  another  in  bending  a  joint  would 
wear  the  bone  with  friction  unless  the  cartilages  were 
very  smooth  and  lubricated  with  a  fluid  called  the  synovial 
fluid.  The  synovial  fluid  would  be  constantly  escaping 
into  the  surrounding  tissues  except  for  the  collarlike  liga- 
ment called  the  capsule,  which  surrounds  the  joint  and  is 
attached  to  each  bone  entirely  around  the  joint  (Fig.  42). 

THOUGHT  QUESTIONS.  —  The  Kinds  of  Joints.  Write  B,  //,  £,  E, 
/,  /Rafter  these  names  according  to  the  kind  of  joint  (ball-and-socket, 
hinge,  gliding,  elastic,  immovable,  or  pivot) :  bones  of  skull,  head 
nodding,  head  turning,  vertebrae,  lower  jaw,  ribs  to  breast- 
bone (Fig.  97),  shoulder,  elbow,  wrist,  fingers,  hip, 
knee,  ankle,  toes. 

« 
Growth  of  Bones.  —  The   blood  vessels  pass    into   the 

bones  from  the  periosteum.  If  the  periosteum  is  removed, 
the  larger  blood  vessels  are  taken  away  and  the  bone  beneath 
it  perishes.  If  the  underlying  bone  is  removed  and  the 
periosteum  left,  the  bone  will  be  replaced.  A  curious  proof 
of  the  active  circulation  in  the  bone  is  furnished  when 
madder  is  mixed  with  the  food  of  pigs.  In  a  few  hours 
the  bone's  become  a  darker  pink  than  usual;  and  if  the 
madder  is  fed  to  the  pigs  for  a  few  days,  their  bones 
become  red.  A  child  grows  in  height  chiefly  during  three 
or  four  months  in  spring  and  summer;  but  the  body 
broadens  and  becomes  heavier  during  autumn. 

Health  of  the  Bones.  —  It  is  plain  that  a  strong  and  free 
circulation  of  pure  blood  contributes  to  the  health  and 


48  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

strength  of  the  bones ;  good  food  and  pure  air  make  pure 
blood.  Impure  food  and  injurious  substances,  like  alcohol, 
tobacco,  and  opium,  weaken  the  bones 
if  they  are  taken  into  the  blood.  Cases 
of  "delayed  union,"  or  slow  mending 
of  broken  bones,  occur  more  often 
with  intemperate  than  with  sober 
people.  This  is  because  the  vital- 
ity of  the  bone  cells  has  been 
weakened  by  the  alcohol.  Why  do 
surgeons  dislike  to  operate  on  an  old 
drunkard  ? 

Deformities.  —  A  bone  may  be 
sound,  yet  deformed  ;  no  human  body 
can  be  perfect  in  function  if  any  part 
of  its  framework  is  deformed.  These 
deformities  may  come  in  various  ways, 
and  the  remainder  of  this  chapter  will 
be  devoted  to  this  topic.  • 

Constant  pressure  in  one  direction 
is  the  usual  cause  of  deformed  bodies. 
This  pressure  may  result  from  :  ( I )  the 
weight  of  the  body  held  in  wrong  po- 
sitions ;  (2)  confining  the  body  by 
bands  or  tight  clothing ;  (3)  unequal 
development  of  muscles  from  work 
which  brings  certain  muscles  constantly 
into  use,  and  leaving  largely  unused 

FIG.  47.  — SIDE  VIEW  OF   the  muscles  that  would  restore  the 
SKELETON. 

balance. 

Posterior  Curvature  of  the  Spine.  — The  spine  (see 
Figs.  39,  47)  has  two  backward  curves  (opposite  chest  and 
hips)  and  two  forward  curves  (at  loins  and  neck).  The 


THE  SKELETON 


49 


deformity  called  posterior  curvature  is  chiefly 
an  exaggeration  of  the  upper  posterior  curve. 
Round  shoulders  is  the  slightest,  and  hunch- 
back the  most  marked,  degree  of  this  deform- 
ity. Causes  :  i,  Bending  over  the  work  while 
either  standing  or  sitting  ;  2,  slipping  down  in 
the  seat,  as  in  Figure  62  ;  3,  working  habitually 
with  the  work  low  in  front,  as  reading  and 
writing  at  too  low  a  desk  (Fig.  60),  or  bending 
over  while  hoeing;  4,  weak  muscles  in  the 
back ;  5,  wearing  shoes  with  high  heels ; 

6,  binding  the  ribs  down  with  tight  clothing ; 

7,  walking  with  the  head  drooped  forward  or 
the  chest  flat.      This  deformity  is  brought 
about  by  stretching  the  ligaments  at  the  back 

side  of  the  spine,  and  by  compressing  the  FlG  ^ 
cartilages  until  they  become  wedge-shaped,  with 
the  thin  part  of  the  wedge  in  front.  The  flex- 
ibility of  the  spine  is  a  great  advantage,  but 
it  increases  the  risk  of  deformity.  One  of 
the  most  serious  evils  of  posterior  curvature 
is  a  flat  chest  and  restricted  breathing. 

Lateral  Curvature  of  the  Spine.  —  A  perfect 
spine  curves  to  neither  side  (see  Fig.  59),  but 
is  perfectly  erect.  The  least  habitual  lateral 
curvature  is  deformity.  Causes  :  I,  writing 
at  a  desk  that  is  too  high  ;  2,  habitually  carry- 
ing a  book  satchel  or  other  weight  in  the 
same  hand ;  3,  riding  horseback  with  a  side 
saddle  ;  4,  carrying  the  head  to  one  side  (Fig. 
58,  Plate  II). 

FlG.  48.  —  Incorrect  posture. 

FIG.  49.  —  Correct,  but  strained  and  stiff.  Compare  position 
of  head,  chest,  and  hips  in  Figs.  48,  49  with  the  vertical  line.  FlG.  49. 


*> 


$O  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

THOUGHT  QUESTIONS.  — The  Skeleton.  1.  Which  part  of  a  verte- 
bra (Fig.  50)  serves  chiefly  for  support  ?  For  attachment  of  muscles  ? 
For  protecting  spinal  cord?  2.  Why  is  it  well  for  the 
spine  to  have  many  instead  of  a  few  joints  ?  3.  Find  by 
bending  your  own  body,  or  by  studying  Figure  39,  which 
part  of  the  spine  allows  least  motion.  Why?  4.  Which 
part  of  spinal  column  is  most  easily  sprained  ?  Which  next? 
5.  Why  is  energy  saved  by  having  a  pivot  joint  at  the 

FIG.  50.  — A   eibow  rather  than  at  the  shoulder?     6.   Why  is  it  better 
VERTEBRA.  .    „       .        .      .  .  ... 

to  have  ball-and-socket  joint  at  shoulder,  and  hinge  joint 

at  elbow,  rather  than  the  reverse  ? 

Tests  for  Lateral  and  Posterior  Curvature.  —  A  strip 
may  be  fastened  with  one  nail  upon  a  post  at  a  height  of 
six  or  eight  feet.  The  end  may  be  turned  down  until  it 
just  touches  the  shoulder.  Turn  and  bring  the  other 
shoulder  under  the  strip ;  if  the  shoulders  are  the  same 
height,  the  spine  is  straight.  If  they  are  of  unequal 
heights,  the  spine  should  be  examined  to  see  whether  it 
forms  a  perfect  vertical  line  (see  Fig.  59).  To  test  for 
posterior  curvature,  stand  facing  the  wall,  with  the  chest 
touching  the  wall,  and  having  the  head  in  its  usual  position. 
If  there  is  no  deformity,  the  face  will  not  touch  the  wall. 

To  overcome  Spinal  Deformities.  — The  work,  or  the  man- 
ner of  doing  the  work,  should  be  so  changed  as  to  give 
extra  labor  to  the  neglected  muscles.  Avoid  the  habits 
mentioned  above  as  causing  deformity.  Sit  and  stand  in 
the  manner  described  in  the  next  paragraph.  Sleeping  on 
the  back  upon  a  hard  mattress  without  a  pillow  tends  to 
cure  posterior  curvature  and  flat  chest. 

The  correct  position  in  standing  is :  chest  forward,  chin 
in,  kips  back  (Figs.  48,  49).  To  sit  correctly,  sit  far  back 
in  the  chair  (Figs.  60,  61,  62)  with  the  body  erect  and  bal- 
anced. In  youth  the  bones  are  soft  and  growing;  they 
will  readily  grow  into  perfect  shape,  and  will  almost  as 
readily  grow  deformed. 


THE  SKELETON  51 

PRACTICAL  QUESTIONS.  —  The  Skeleton.  1.  What  kind  of  a 
chair  back  causes  one  to  slide  forward  in  the  seat  ?  2.  What  fault 
in  sitting  is  made  necessary  by  using  a  chair  with  so  large  a  seat  that 
the  front  edge  strikes  the  occupant  behind  the  knee  ?  3.  Why  is  the 
shoulder  more  often  dislocated  than  the  hip  ?  4.  High  pillows  may 
cause  what  deformity  ?  5.  Find  three  bones  in  the  body  not  attached 
to  other  bones.  Find  twenty-five  bones  attached  to  other  bones  by 
one  end  only  (Figs.  33  and  47).  6.  What  deformities  may  result 
from  urging  a  young  child  to  stand  or  walk  ?  7.  Which  bone  is 
most  often  broken  by  falling  upon  the  shoulder  ?  8.  Where  in  bones 
is  fat  stored  for  future  use  ?  9.  Ligaments  grow  very  slowly.  Why  is 
the  recovery  from  a  sprain  often  tedious  ?  10.  How  many  of  your 
classmates  habitually  slide  forward  while  sitting  ?  Count  and  report. 

11.  When  the  school   is  marching  out,  count  those  who  walk  with 
head  protruded  (Fig.  48).     Report. 

REVIEW  QUESTIONS.  —  Chapter  I.  1.  Write  the  names  of  the  follow- 
ing animals  in  a  list  according  to  the  degree  in  which  they  resemble 
man,  and  give  the  reason  for  the  order  :  horse,  crawfish,  bird,  ameba, 
dog.  2.  Describe  the  ameba,  and  tell  how  it  moves,  eats,  breathes, 
and  multiplies.  3.  What  in  man's  body  resembles  the  ameba  ? 
4.  How  is  a  cut  in  the  flesh  repaired  ?  5.  Of  what  does  a  living 
cell  chiefly  consist  ?  What  is  always  found  in  the  cell  ?  What  usually 
surrounds  it?  6.  Define  cell;  fiber;  tissue;  membrane.  7.  Com- 
pare the  cell  community  with  a  community  of  people.  8.  What 
kind  of  cell  in  the  human  body  corresponds  to  a  railroad  man  ;  a  farmer ; 
a  soldier ;  a  Jack-at-all-trades ;  an  official  or  teacher  ?  9.  Show  the 
advantage  of  division  of  labor. 

1.  Define     anatomy;     physiology;     hygiene;     organ;     function. 

2.  Name  the  three  kingdoms  into  which  all  material  things  are  divided. 

3.  Define  organic ;  inorganic.       4.  State  the  chief  difference  between 
animals  and  plants.       5.  Why  must  there  be  different  tissues  in  the 
body?      6.  Into  what  two  general  classes  are  the  seven  tissues  divided, 
and  why?      7.  Name  the  two  master  tissues.     What  is  their  work? 
8.  How  long  are  the  longest  branches  of  the  nerve  cells  ?      9.  Define 
nerve;  motor  fibers;  sensory  fibers.       10.  Name  the  five  supporting 
tissues.      11.  What  are  the  two  kinds  of  fibers  in  connective  tissue  ? 

12.  State  a  fact  which  shows  the  great  abundance  of  connective  tissue. 

13.  From  what  tissue  is  fatty  tissue  developed  ?     How  ?      14.  Of  what 
does  epithelial  tissue  consist  ?    Where  is  it  found  ?     How  is  it  nour- 
ished ?      15.  What  is  the  purpose  of  each  of  the  two  classes  of  epithe- 
lial cells?      16.  What  is  the  structure  of  cartilaginous  tissue?     What 
are  the  two  varieties  of  it  ?      17.  What  is  found  in  the  larger  canals 


$2  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

of  osseous  tissue  ;  the  smallest  canals  ;  the  minute  cavities  ?  18.  What 
is  oxidation  ?  19.  Name  six  poisons. 

Chapter  II.  1.  What  is  the  chief  function  of  the  skin?  2.  What 
is  the  structure  of  the  dermis  and  epidermis?  What  and  where  are  the 
papillae?  3.  Describe  the  cells  of  the  epidermis  near  the  surface;  the 
deeper  cells;  the  lowest  cells.  What  are  albinos?  4.  From  what 
does  a  hair  grow ?  5.  Explain  gray  hair;  baldness;  hair  standing  on 
end.  6.  From  what  does  the  nail  grow?  How  fast  does  it  grow? 
7.  Into  what  do  the  oil  glands  generally  empty?  8.  What  is  the  use 
of  the  oil?  Describe  a  sweat  gland.  9.  What  does  perspiration  con- 
tain? How  is  the  amount  of  perspiration  controlled?  10.  What  is  the 
anatomy  of  freckles  ;  warts  ;  moles  ;  scars  ;  proud  flesh  ;  pimples  ;  black 
heads?  11.  What  are  the  uses  of  the  muscles  in  the  skin?  Of  the 
nerves?  12.  What  are  hot  spots  ;  cold  spots?  (Fig.  162.)  13.  How 
does  the  skin  help  to  regulate  the  heat  of  the  body?  14.  What  informa- 
tion does  the  feeling  that  we  are  hot  or  cold  give  us?  15.  How  does 
alcohol  affect  the  feeling  of  warmth  ? 

1.  Discuss  the  effects  upon  the  skin  of  outdoor  and  indoor  life. 
2.  Show  the  need  of  training  the  skin.  3.  What  are  the  characteristics 
of  a  vigorous  skin?  4.  Show  why  it  is  necessary  to  counteract  the 
effects  of  civilized  life  upon  the  skin.  5.  State  the  benefit  of  a  warm 
bath  and  the  time  and  manner  of  taking  it.  6.  State  the  benefits  of 
cold  baths.  7.  How  may  one  become  used  to  them?  8.  Discuss  the 
relation  of  material  (cotton,  linen,  woolen),  color  (dark,  light),  and 
texture  (tight,  loose)  of  clothing  to  climate  and  weather. 

Chapter  III.  1.  Study  by  observation  your  arm  and  hand,  and 
state  all  that  you  have  learned  about  it.  2.  What  deposits  the  lime  in 
the  bones?  3.  Why  is  a  skeleton  needed?  4.  Name  the  three  forms 
and  the  three  uses  of  bones.  5.  Describe  all  that  can  be  seen  in  a  long 
bone  sawed  lengthwise.  6.  Describe  experiments  on  the  composition 
of  bones.  7.  How  is  the  skeleton  subdivided?  8.  State  the  parts  of 
a  vertebra  and  the  use  of  each  part.  9.  What  are  the  attachments  of 
the  twenty-four  ribs?  10.  Describe  and  locate  the  tongue  bone ;  the 
collar  bone;  the  shoulder  blade;  the  hip  bone;  the  cranium.  Com- 
pare the  bones  of  the  arm  and  leg.  11.  State  name  and  description 
and  give  example  of  each  kind  of  joint.  12.  Why  is  periosteum  nec- 
essary for  the  growth  of  the  bone?  13.  What  is  most  necessary  for 
the  health  of  the  bones?  14.  Give  several  sources  of  pressure  that 
may  deform  the  bones.  15.  Give  seven  causes  of  posterior  curvature 
of  the  spine.  Give  four  causes  of  lateral  curvature.  16.  Describe  the 
correct  position  in  standing ;  in  sitting.  17.  Locate  :  scapula,  sternum, 
patella,  tarsus  (see  Figs.  33,  47).  , 


CHAPTER  IV 

THE  MUSCLES 

Uses  of  Muscles.  —  The  bones  give  the  body  its  general 
proportions  ;  the  muscles  give  its  graceful  curves.  Every 
muscle  is  a  living  machine  ;  a  bone  is  a  lever  for  a  muscle 
or  group  of  muscles  to  set  in  motion.  The  muscles  weigh 
more  by  far  than  any  other  set  of  organs  in  the  body  ;  they 
constitute  forty-one  per  cent,  or  almost  half,  of  the  bodily 
weight.  The  use  of  the  muscles  is  to  obtain  and  prepare 
the  food  which  the  body  needs.  They  are  necessary  in 
chewing,  swallowing,  and  in  digesting  the  food  ;  in  making 
the  blood  circulate,  in  breathing,  in  every  change  in  the 
expression  of  the  face,  and  in  every  variation  in  the  tone 
of  voice.  When  no  motion  whatever  can  be  discovered 
in  the  body,  we  know  it  is  dead.  You  learned  while 
studying  the  bone.s  of  the  arm  that  there  are  at  least  two 
muscles  attached  to  a  bone  to  move  it  in  opposite  direc- 
tions. Since  there  are  two  hundred  and  six  bones,  you 
are  not  surprised  to  learn  that  to  move  the  bones  and 
accomplish  the  various  purposes  just  stated,  there  are 
more  than  five  hundred  skeletal  muscles. 

Two  Kinds  of  Muscles. — All  muscles  are  controlled  by 
means  of  the  nervous  system.  Some  of  them  are  directed 
by  parts  of  the  brain  that  work  consciously  ;  others  are 
controlled  by  the  spinal  cord  and  the  parts  of  the  brain 
that  work  unconsciously.  Those  of  the  first  kind  are 
usually  controlled  by  the  will.  Although  they  sometimes 

53 


54 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


act  involuntarily,  they  are  called  voluntary  muscles.  Those 
of  the  other  kind  are  never  controlled  by  the  will,  and  are 
called  involuntary  muscles.  We  cannot  cause  them  to  act, 
nor  can  we  prevent  them  from  acting.  They  contract 
more  slowly  than  the  voluntary  muscles. 

Structure  of  Voluntary  Muscles.  —  A  beefsteak  is  seen  to 
be  chiefly  red,  although  parts  of  it  are  white  or  yellowish. 

The  white  or  yellowish  flesh 
is  fat ;  the  red,  lean  flesh  is 
voluntary  muscle.  If  a  piece 
of  beef  is  thoroughly  boiled, 
it  may  be  easily  separated 
into  bundles  the  size  of  large 
cords.  These  bundles  may, 
by  the  use  of  needles,  be 
FIG.  51.  — MUSCLE  BUNDLE  bound  to-  picked  apart  and  separated 

gether  by  connective  tissue  sheaths. 

into  threadlike  fibers.  These, 

under  a  magnifying  'glass,  may  be  separated  into  fine 
strands  called  fibrils.  These  last  are  the  true  muscle  cells  ; 
they  are  shown  by  the  microscope  to  be  crossed  by  many 
dark  lines  (see  colored  Fig.  12).  Hence  voluntary  muscles 
are  called  striated  or  striped  muscles.  Prolonged  boiling 
and  patient  picking  with 
a  needle  are  needed  to 
dissect  muscle,  because 
the  bundles  are  held 
together  by  thin,  glisten- 
ing sheets  of  connective 
tissue  by  which  they  FIG.  52.  — INVOLUNTARY  MUSCLE  CELLS  (or 
are  surrounded.  This  fibers)' 

connective  tissue  surrounds  and  holds  in  place  the  separate 
fibers  of  each  bundle.  The  voluntary  muscles  move  the 
bones,  and  are  located  in  the  limbs  and  near  the  surface 


THE  MUSCLES 


55 


of  the  trunk ;  the  involuntary  muscles  are  chiefly  in  the 
cavity  of  the  trunk. 

Structure  of  Involuntary  Muscles.  — 
The  fibrils  of  these  muscles  are  spindle- 
shaped  (see  Fig.  52).  There  are  no 
cross  lines  on  the  fibrils,  and  involun- 
tary muscles  are  called  smooth  or  tin- 
striped  muscles.  The  involuntary  mus- 
cles belong  to  the  internal  organs,  and 
relieve  the  will  of  the  responsibility  and 
trouble  of  the  activity  of  these  organs ; 
otherwise,  the  mind  would  have 
time  for  voluntary  actions. 


no  FIG.  53.  —  Two  MUS- 
CLE FIBERS  OF 
HEART. 


THOUGHT  QUESTIONS.  —  Classification  of  Some  of  the  Muscles. 
Mark  /  for  involuntary  and  V  for  voluntary  after  the  appropriate 
muscles  in  the  following  list :  — 

Muscles  for  chewing.  Muscles  for  swallowing.  Muscles  of  the 
heart.  Muscles  that  move  arms.  Muscles  for  breathing.  Muscles 
in  the  skin  that  cause  the  hair  to  stand  on  end.  Muscles  that  move 
eyelids.  Muscles  that  contract  pupil  of  eye.  Muscles  for  talk- 
ing. Muscles  that  contract  and  expand  the  arteries  (in  blushing  and 
turning  pale).  Muscles  that  move  eyeball.  Muscles  that  give 
expression  to  the  face. 

Tendons. —  The  connective  tissue  which  binds  the  fibers  of 
muscles  into  bundles,  and  forms  sheaths  for  the  bundles, 
extends  beyond  the  ends  of  the  muscles  and  unites  to  form 
tough,  inelastic  white  cords  called  tendons.  Some  muscles 
are  without  tendons,  and  are  attached  directly  to  bones. 
Study  the  figures  and  find  examples  of  this  (see  Figs. 
63,  64).  To  realize  the  toughness  of  tendons,  feel  the 
tendons  under  the  bent  knee  or  elbow  where  they  feel 
almost  as  hard  as  wires.  The  tendons  save  space  in  places 
where  there  is  not  room  enough  for  the  muscles,  and 
permit  the  bulky  muscles  to  be  located  where  they  are 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


Ligament 


-, — EXTENSOR 
I     TENDON 


out  of  the  way.     Wherever  the  tendons  would  rise  out 
of  position  when  a  joint  is  bent,  as  at  the  wrist  and  ankle, 

they  are  bound  down  by  a 
ligament  (Figs.  67,  69,  Chart). 
Some  of  the  Important 
Muscles.  —  The  gullet  is  a 
fleshy  tube  of  involuntary 
muscle ;  successive  rings  of 
muscle  contract  during  the 
act  of  swallowing.  It  is  the 
swiftest  in  action  of  all 
the  involuntary  muscles.  The 
muscular  walls  of  the  stomach 
and  intestines  contract  in 
EXTENSOR  waves  that  follow  one  another 

TENDON 

along  the  food  tube.     This  is 
called  peristalsis. 

Some  muscles  are  hollow, 
as  the  heart.  Circular  mus- 
cles, called  sphincter  muscles, 
are  found  around  the  mouth 

and  eyes.     Attached  to  the  circular  muscle  of  the  mouth 

are   little  muscles   running  off  to 

various   parts    of    the   bones   and 

skin  of  the  face  (see  Chart  of  the 

Muscles).     The  facial  muscles  are 

called  muscles  of  expression.     Some 

draw  the  corners  of  the  mouth  down, 

others  draw  them  up,  and  others 

widen  the  mouth  as  in  smiling. 
There  are  large  muscles  in  the 

calf  of  the  leg  that  raise  the  heel 

FIG.  55.  — For  blackboard.  Bl 
and  Cause  the  person  tO  Stand  Upon       CEPS  relaxed  and  contracted 


FIG.  54.  — TENDONS   OF   INDEX 
FINGER. 


THE  MUSCLES  57 

the  toes  (see  Fig.  71).  It  is  attached  to  the  heel  by  the 
largest  tendon  in  the  body.  The  cavity  of  the  trunk  is 
divided  into  the  chest  and  abdomen  by  the  broadest  mus- 
cle in  the  body ;  it  is  called  the  diaphragm,  and  is  the  most 
important  of  the  breathing  muscles.  The  longest  muscle 
in  the  body  is  called  the  tailors  muscle ;  it  is  used  in 
crossing  the  legs  (see  Fig.  68,  Chart).  Muscles  like  the 
tailor's  muscle,  that  go  around  a  limb,  twist  or  rotate  the 
limb  when  they  contract.  Muscles  that  extend  straight 
along  the  limb  either  bend  it  and  are  called  flexors,  or 
straighten  it  and  are  called  extensors.  Many  of  the  muscles 
are  arranged  in  pairs  and  cause  motion  in  opposite  di- 
rections ;  they  are  said  to  be  antagonists.  The  action  of 
the  biceps  has  been  described.  Its  antagonist  is  the 
triceps  on  the  back  of  the  arm  (Fig.  67,  Chart). 

THOUGHT  QUESTIONS. —Voluntary  Muscles.  Locate  the  muscles 
having  the  functions  named  in  the  following  list.  Locate  them  by 
performing  the  action  and  feeling  the  muscle  with  your  hand.  Be 
ready  to  point  them  out  on  the  Chart  of  the  Muscles.  Locate  the 
muscle  (or  muscles)  that :  — 

1.  Lifts  the  whole  arm  outward  and  upward.  2.  Draws  it  down- 
ward and  forward.  3.  Draws  it  downward  and  backward.  4.  Bends 
the  elbow.  5.  Straightens  the  elbow.  6.  Bends  the  fingers. 
7.  Straightens  the  fingers.  8.  Turns  the  head.  9.  Draws  the 
shoulders  back.  10.  Bends  the  knee.  11.  Straightens  the  knee. 
12.  Raises  the  toes.  13.  Raises  the  body  on  the  toes.  14.  Crosses 
the  legs. 

How  the  Muscles  grow  Stronger.  —  Nature  has  provided 
that  any  part  of  the  body  shall  receive  more  blood  when  it 
is  working  than  when  it  is  resting.  When  it  works  the 
hardest,  the  blood  tubes  expand  the  most,  and  its  blood 
supply  is  greatest.  So  whenever  a  muscle  is  used  a  great 
deal,  an  unusual  amount  of  material  is  carried  to  it  by 
the  blood,  the  cells  enlarge  and  multiply,  and  the  muscle 


58  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

grows.  The  walls  of  the  capillaries  are  so  thin  that  the 
food  which  is  in  the  blood  readily  passes  from  them  to 
the  muscle.  Because  of  the  oxidation  taking  place,  a 
working  muscle  is  warmer  than  one  at  rest.  By  use  a 
muscle  grows  large,  firm,  and  of  a  darker  red ;  by  disuse, 
it  becomes  small,  flabby,  and  pale. 

Muscles  can  be  developed  much  more  completely  in  youth 
while  the  body  is  growing  than  later,  and  they  retain  the 
development  longer.  Yet  even  after  we  are  grown  the 
muscle  fibers  sometimes  multiply  enormously.  In  youth 
the  body  can  be  readily  stunted  by  tasks  too  heavy  for 
children,  as  those  in  a  factory  or  a  mine,  or  on  a  farm. 
Muscles  that  are  strained  or  that  are  used  so  much  that 
they  wear  out  faster  than  they  can  be  fed  by  the  blood, 
will  diminish  in  size  instead  of  grow. 

Why  the  Muscles  work  in  Harmony.  —  There  are  about 
five  hundred  muscles,  yet  the  body  is  capable  of  many 
thousands  of  different  motions.  This  is  because  of  vari- 
ous combinations  in  using  the  muscles.  Some  acts  require 
a  great  number  of  muscles.  When  a  boy  throws  a  stone  y 
almost  every  part  of  the  body  is  concerned  in  the  action. 
His  arm,  his  legs,  his  eyes,  the  breathing,  the  beating 
of  the  heart,  are  all  modified  to  assist  in  the  effort. 
How  is  it  brought  about  that  they  all  act  at  the  same 
time  and  in  perfect  harmony  ?  This  occurs  because  all 
the  muscles  are  connected  with  the  brain  by  nerves. 
When  the  boy  wills  to  throw  the  stone,  nerve  impulses 
are  sent  to  all  the  organs  that  can  assist,  and  they  are 
excited  to  just  the  amount  of  action  needed.  Of  course, 
long  practice  is  needed  to  train  the  nerves  and  muscles  for 
any  complicated  action.  Walking  requires  the  action  of 
dozens  of  muscles,  and  it  is  not  strange  that  many 
months  are  required  in  learning  to  walk  well. 


THE  MUSCLES 


59 


The  Nerve  Impulse  and  the  Contraction.  —  Each  nerve 
that  goes  to  a  muscle  is  composed  of  many  fibers ;  the 
fibers  soon  separate  and  go  to  all  parts  of  the  muscle, 
and  each  muscle  fiber  receives  its  nerve  fiber  (see  Fig.  56). 
The  muscles  never  contract  of  their  own  accord,  any  more 
than  a  telephone  bell  rings  of  its  accord.  The  brain  sends 
nerve  impulses  to  the  muscles,  each  fiber  is  stimulated  at 
once,  and  all  the  fibers  shorten 
and  thicken  together,  causing 
the  shortening  and  thicken- 
ing that  is  so  readily  noticed 
in  the  whole  muscle.  This 
change  is  spoken  of  as  con- 
traction ;  but  since  the  mus- 
cle does  not  become  smaller, 
the  word  may  be  misleading. 
When  the  muscle  shortens, 
it  thickens  in  proportion  and 
occupies  as  much  space  as  it 
did  when  relaxed. 

Where  does  Muscular  En- 
ergy come  from?  —  In  the 
ringing  of  an  electric  bell, 
the  wire  takes  the  electric 
energy  from  the  battery  to  the  bell ;  and  the  battery,  not 
the  bell,  furnishes  the  energy  which  moves  the  clapper. 
The  nerve  does  not  furnish  the  energy  which  the  muscle  uses 
when  contracting.  The  muscle  cells  have  already  stored  up 
energy  from  the  food  and  oxygen  broitght  to  them  by  the 
blood.  Similarly,  when  a  gun  is  fired,  the  energy  was 
already  stored  in  the  cartridge  and  was  only  set  free  by 
pulling  the  trigger. 

How  a  Muscle  stays  Contracted.  —  The  muscle  relaxes  at 


FIG.  56.— MOTOR  NERVE  FIBERS  end- 
ing among  fibers  of  voluntary  muscle. 


60  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

once  after  contraction ;  and  in  order  to  keep  it  contracted, 
impulses  must  be  sent  in  quick  succession,  causing  in  fact 
many  contractions ;  the  effect  of  this  is  sometimes  visible, 
as  the  trembling  of  the  muscle. 

Muscular  Tone.  —  Relaxation  is  the  usual  condition  of  a 
muscle,  yet  a  healthy  muscle  even  when  relaxed  is  ahvays 
exerting  a  slight  pull  upon  the  bones.  This  state  of  slight 
tension  is  called  muscular  tone.  It  is  necessary  in  order 
to  keep  the  muscles  prepared  for  promptness  and  steadi- 
ness of  movement.  This  tone  causes  a  sleeping  person 
to  assume  a  slightly  flexed  position ;  it  causes  cuts  in 
the  flesh  to  gap  open ;  it  causes  the  muscles  to  pull  a 
dislocated  arm  or  leg  beyond  the  socket,  so  that  con- 
siderable force  is  necessary  to  get  it  into  position  to 
slip  into  its  socket  again.  To  keep  muscles  in  this 
condition  slight  nerve  currents  are  being  continually 
sent  to  them. 

What  causes  Fatigue.  —  Fatigue  or  exhaustion  is  due  to 
the  production  of  certain  poisonous  waste  products,  which 
result  from  the  activity  of  the  muscles,  and  which  have 
the  effect  of  paralyzing  the  nerves  in  the  muscles.  If 
the  worker  rests  for  a  time,  the  blood  will  take  away  these 
waste  products;  and  the  impulses  sent  along  the  nerves 
will  easily  cause  the  muscle  to  work  again.  Can  you 
explain  why  it  is  less  fatiguing  to  walk  for  an  hour  than 
to  stand  perfectly  still  for  ten  minutes  ? 

How  the  Activity  of  One  Muscle  may  make  Another 
Muscle  Tired. -  —  The  fatigue  poisons  sent  into  the  blood 
current  by  a  few  muscles  working  for  a  long  time,  may  be 
distributed  all  over  the  body,  and  fatigue  reaches  not  only 
the  other  muscles,  but  the  brain  also,  so  that  rest  and  sleep 
become  imperative.  Runners  have  been  known  to  drop 
dead  after  long  running.  Horses  have  died  suddenly  from 


THE  MUSCLES  6l 

overexertion.  Muscular  exertion  strengthens  the  lungs 
and  skin  by  arousing  them  to  their  most  powerful  activity, 
that  they  may  free  the  body  of  the  waste  products. 

A  grave  danger  from  athletics  is  that  of  developing 
the  muscles,  including  the  heart,  to  an  enormous  extent, 
by  training;  then  when  training  ceases  the  muscles  undergo 
fatty  degeneration  from  disuse.  Heart  disease  and  other 
troubles  may  follow.  Most  athletes  die  young,  killed  by 
trying  to  turn  their  bodies  into  mere  machines  for  running, 
boxing,  rowing,  instead  of  living  complete  lives.  In  phys- 
ical culture,  it  is  necessary  to  develop  lungs,  nerves,  etc., 
equally  with  the  muscles  ;  but  it  is  also  dangerous  to 
develop  immense  lungs  and  suddenly  to  cease  activities 
that  call  them  into  use.  Portions  of  the  lung  tissue  may 
then  shrink  together  and  become  diseased.  Abrupt 
changes  of  habits  are  dangerous  to  the  health.  A  more 
common  cause  of  fatty  degeneration  of  the  muscles  is  alcoJiol, 
taken  in  the  form  of  beer  and  other  drinks. 

THOUGHT  QUESTIONS.  —  The  Work  of  Muscles.  1.  By  studying 
the  Chart  of  the  Muscles,  apply  these  four  pairs  of  adjectives  in  their 
proper  places  in  the  lines  below:  long  and  round;  thin  and  flat; 
short  and  narrow  ;  broad  and  flat :  — 

The  muscles  of  the  face  are and . 

The  muscles  of  the  cranium  are and -. 

The  muscles  of  the  trunk  are and . 

The  muscles  of  the  limbs  are and . 

2.  Span  the  biceps,  holding  tip  of  finger  in  elbow  and  thumb  farther 
up  the  arm.  How  many  inches  of  its  length  does  the  biceps  lose  by 
contracting  ?  3.  Why  is  round  steak  usually  the  toughest  steak  ?  The 
most  nutritious  ?  4.  Why  is  a  fowl's  leg  dark  meat,  although  its  breast 
and  wing  are  white  meat  ?  Why  is  a  fowl's  breast  white  and  a  dove's 
breast  dark  ?  (Page  58,  line  5.)  5.  Which  muscles  must  be  strength- 
ened to  overcome  round  shoulders  and  posterior  curvature  of  the  spine  ? 

6.  The  muscles  that  move  the  fingers  and  wrist  are  in  the ;  the 

muscles  that  move  the  forearm  are  in  the ;  the  muscles  that  move 

the  upper  arm  are  in  the (see  Chart  of  Muscles). 


62  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

How  Muscular  Activity  helps  the  Health.  —  Life  is 
change,  stagnation  is  death.  Muscular  activity  uses  up  the 
food,  gives  a  good  appetite,  and  sets  the  digestive  organs  to 
work ;  it  uses  up  the  oxygen  and  sets  the  lungs  to  work ; 
but  most  of  all,  every  contraction  of  a  muscle  helps  the 
blood  to  flow.  As  a  muscle  contracts,  it  presses  upon 
the  veins  and  lymphatics,  and,  by  this  pressure,  forces  the 
blood  and  lymph  along.  In  any  ordinary  activity,  dozens 
of  muscles  are  being  used.  That  the  effect  upon  the  cir- 
culation is  very  powerful,  is  shown  by  the  rosy  skin,  deep 
breathing,  and  rapid  heart  beat.  The  many  benefits  of  an 
active  circulation  of  the  blood  and  lymph  will  be  discussed 
in  the  next  chapter. 

Advantages  of  Work  and  Play  over  Gymnastic  Exer- 
cises. —  Lord  Rosse  of  Ireland,  during  the  famine  of  1847, 
fed  a  great  number  of  people  who  were  out  of  work.  To 
save  the  self-respect  of  the  men  and  prevent  their  forming 
habits  of  idleness,  he  caused  a  number  of  them  to  dig  holes, 
and  another  set  of  men  to  fill  them  up.  When  each  set  of 
men  learned  what  the  other  men  were  doing,  they  refused 
to  continue  in  such  useless  labor.  The  interest  that 
comes  from  doing  something  useful,  makes  exercise  doubly 
beneficial  to  the  health.  The  lifting  of  dumb-bells,  Indian 
clubs,  and  pulley  weights,  and  letting  them  down  again, 
tends  to  become  very  irksome,  even  though  done  with  the 
knowledge  that  the  exercise  will  benefit  the  health.  Useful 
labor  and  games  place  definite  objects  in  view  and  do  not 
require  so  great  an  effort  of  the  will  nor  exhaust  the  nerves 
so  much  as  mere  exercise.  The  interest  in  the  work  or  the 
game  serves  to  arouse  all  the  nerves  and  muscles  to  work 
in  harmony. 

An  Advantage  of  Gymnastics  over  Work  and  Play.  — 
Gymnastics  can  furnish  any  required  variety  of  exercises 


THE  MUSCLES  63 

and  can  develop  exactly  the  muscles  that  need  development 
and  leave  those  idle  that  have  become  overdeveloped 
by  doing  constantly  one  kind  of  work  or  playing  continually 
the  same  game.  The  deformity  of  a  flat  chest  (and  round 
shoulders  which  always  accompany  it)  does  not  so  often 
indicate  a  weak  chest  or  small  lungs  as  it  indicates  weak 
or  relaxed  muscles  of  the  back  and, the  habit  of  sitting  in 
a  relaxed  position  at  work.  Such  a  person  may  have  large 
lungs,  but  he  is  in  the  habit  of  carrying  them  too  far 
behind.  The  deformity  may  result  from  constantly  study- 
ing or  reading,  keeping  accounts,  or  rowing  a  boat.  But 
the  condition  is  nearly  as  common  among  farmers  as 
among  students  and  business  men,  because  many  of  them 
think  they  have  to  stoop  over  while  plowing  or  hoeing,  or 
while  riding  on  a  wagon  seat  without  a  back.  The  chest 
can  be  held  up  even  while  hoeing.  Round  shoulders  not 
only  give  an  awkward  appearance,  but  invite  disease  of  the 
lungs.  To  overcome  this  deformity,  special  exercise  for 
strengthening  the  muscles  of  the  back  should  be  taken. 
Chopping  wood  with  a  light  ax  strengthens  the  muscles 
that  draw  the  shoulders  down,  as  the  strength  is  exerted 
in  striking  the  blow.  Using  a  heavy  ax  stretches  the 
muscles  that  lift  and  draw  back  the  shoulders,  as  the 
strength  is  exerted  chiefly  while  lifting  the  ax.  Gymnastic 
exercise  is  not  wholly  an  artificial  custom.  Cats  stretch 
themselves,  stretching  each  leg  in  succession ;  many 
animals  gambol  and  play.  A  gymnastic  drill  in  school, 
taken  to  music  and  with  large  numbers  of  pupils  in  the 
drill  is  interesting  as  work  or  play,  and  should  not  be 
neglected  for  any  study,  however  important. 

Heredity. — A  well-developed  man  of  one  hundred  and 
fifty  pounds  weight  should  have  sixty  pounds  of  muscles. 
The  proportion  is  often  different  in  the  puny  bodies  of  the 


64  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

average  civilized  man,  such  as  clerks,  merchants,  lawyers, 
and  other  men  with  sedentary  occupations  ;  their  bodies  are 
as  likely  to  be  lean  and  scrawny  or  fat  and  flabby  as  to  be 
correctly  proportioned.  Why  does  a  natural  man  have 
sixty^  pounds  of  muscles  instead  of  twenty  pounds  of 
puny  strings  such  as  would  have  sufficed  for  a  clerk, 
student,  or  a  writer?  This  is  because,  in  his  native  con- 
dition, he  had  to  seek  his  food  by  roaming  through  the 
forest,  contending  with  wild  beasts  or  with  other  savage 
men,  often  traveling  many  miles  a  day,  climbing 
trees,  etc. 

Attempting  an  Impossibility.  —  //  is  impossible  for  the 
human  body  to  change  greatly  in  a  feiv  hundred  years. 
The  body  of  man  served  him  for  many  ages  for  the  man- 
ner of  life  outlined  above.  It  was  suited  for  these  condi- 
tions, and  the  muscles  and  the  organs  that  support  them 
cannot  accommodate  themselves  to  changed  conditions  in  a 
few  generations.  It  has  only  been  a  few  hundred  years 
since  the  ancestors  of  the  Britons  and  Germans,  for  in- 
stance, were  running  wild  in  the  German  forests,  clad  in 
the  skins  of  wild  beasts.  Yet  civilized  man  lets  his  muscles 
fall  into  disuse,  he  takes  a  trolley  car  or  horse  vehicle  to  go 
half  a  mile,  an  elevator  to  climb  to  the  height  of  thirty  feet. 
He  neglects  all  his  muscles  except  those  that  move  the 
tongue  and  the  fingers  of  the  right  hand.  He  never  makes 
enough  exertion  to  cause  him  to  draw  a  deep  breath,  and 
his  lungs  contract  and  shrivel.  He  seldom  looks  at  any- 
thing farther  than  a  few  inches  from  his  nose,  and  his  eyes 
become  weak.  At  the  same  time  that  he  neglects  his 
muscles  and  his  lungs,  he  overworks  his  brain  and  his 
stomach ;  yet  he  expects  his  body  to  undergo  the  rapid 
changes  to  suit  the  demands  of  his  life.  Such  rapid  changes 
in  the  human  race  are  impossible. 


THE  MUSCLES  65 

Health  and  Modern  Life.  —  It  has  been  said  that  one 
third  of  the  maladies  with  which  human  beings  are  afflicted 
are  the  result  of  too  much  eating,  another  third  of  too  little 
muscular  work,  while  all  the  other  causes  of  ill  health  com- 
bined are  necessary  to  produce  the  remaining  one  third. 
It  is  estimated  that  there  are  twenty-seven  million  cases  of 
sickness  in  the  United  States  annually,  and  of  these  one 
million  are  chronic  invalids. 

Common  Sense  and  Health.  —  The  average  man  who 
finds  himself  sick  does  not  appeal  to  common  sense  and 
the  science  of  hygiene,  but  to  a  mysterious,  nauseating,  or 
stimulating  drug,  or  a  bowel-convulsing  mineral  spring.  He 
may  get  temporary  relief  in  some  way,  then  he  returns  to 
his  usual  routine  and  goes  on  making  himself  sick  again  by 
his  bad  habits.  This  man  would  not  feed  his  overworked 
horsre  tonics  and  stimulants  in  order  to  get  more  work  out 
of  him,  nor  would  he  expect  to  improve  the  health  of  the 
animal  by  the  purchase  of  a  new  whip.  Yet  the  tonics 
and  alcoholic  drinks  used  by  man  are  no  better  than  a 
whip  ;  they  get  strength  out  of  instead  of  putting  strengtJi  into 
him.  A  man  who  owns  a  sick  horse  changes  the  manner 
of  using  him,  or  turns  him  out  to  pasture.  An  invalid 
man  must  likewise  make  radical  changes  in  his  manner  of 
living.  He  should  return  to  simple,  natural  food  such  as 
his  ancestors  ate,  use  his  brain  less,  his  muscles  more,  and 
live  more  in  the  fresh  air.  He  must  cease  to  cultivate 
sickness  and  begin  to  cultivate  health. 

Care  of  Health  a  Duty.  —  A  man  in  a  large  city  pur- 
chased a  beautiful  horse  and  rode  him  daily  in  the  parks 
and  streets.  Soon  his  business  took  all  his  time,  and  he 
seldom  rode.  The  horse  stamped  impatiently  in  his  stall. 
When  his  friends  said  he  should  not  treat  the  horse  so,  he 
began  to  take  daily  rides  again ;  but  soon  concluded  that 


66  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

it  was  time  to  sell  the  horse,  if  he  had  to  devote  himself 
to  the  comfort  and  health  of  the  horse.  The  man  is  now 
fat,  limping,  and  rheumatic.  This  incident  is  related  to 
illustrate  how  a  man  will  sometimes  take  better  care  of 
a  horse's  health  than  of  his  own.  The  rides  would  have 
been  as  good  for  him  as  for  the  horse. 

Many  people  say  they  cannot  afford  to  take  care  of  their 
health.  They  say  their  duty  to  others  requires  them  to 
neglect  themselves.  A  man  who  was  bookkeeper  in  a 
bank  at  a  salary  of  two  hundred  dollars  a  month  was  taken 
with  a  chronic  cough.  His  friends  said  he  must  take  a 
few  months'  vacation  and  become  strong  again.  He  re- 
plied that  his  duty  to  his  family  forbade  it;  some  of  his 
daughters  were  just  grown  and  needed  to  dress  well  in 
society.  Within  a  year  he  died,  and  his  daughters  had 
to  work  for  a  living,  one  working  as  a  seamstress,  another 
as  a  clerk  in  a  dry-goods  store.  Our  duty  to  others 
requires  that,  first  of  all,  we  take  care  of  our  bodies. 

Many  men  have  by  overwork  made  fortunes  of  millions 
of  dollars,  and  have  afterward  spent  immense  sums  for 
treatment  and  traveled  over  the  world  seeking  to  regain 
health,  but  failed  to  find  it.  One  of  the  richest  men  in 
America  ate  hardly  anything  more  than  a  little  parched 
toast  for  years  before  he  died.  Another  has  lost  all  the  hair 
on  his  head  from  indigestion,  and  his  wife  will  not  trust  any 
one  to  prepare  food  for  him  but  herself.  Unless  he  chops 
wood  or  takes  other  exercise  every  day,  every  morsel  of 
food  he  eats  is  a  torture  to  him.  A  man  that  does  not  see 
that  sound  health  is  the  most  valuable  thing  in  the  world, 
except  a  clear  conscience,  is  in  danger  both  of  wrecking  his 
own  happiness  and  of  failing  in  his  duty  to  others. 

THOUGHT  QUESTIONS. — Shoes.  1.  What  the  faults  of  shoes  may 
be  in  size;  shape;  sole;  heel;  toe;  instep.  2.  Name  deformities  re- 


THE  MUSCLES  6? 

suiting  to  skin  of  foot ;  nails  ;  joints  ;  arch  ;  ankle ;  spine.  3.  State  effects 
of  uncomfortable  shoes  on  muscular  activity;  mind  and  disposition. 
4.  State  effect  of  aversion  to  walking,  on  musoles  ;  circulation.  5.  If 
a  shoe  is  too  loose,  it  slips  up  and  down  at  the  heel  and  chafes  the  skin 
there  ;  if  too  tight,  ther.e  is  pres- 
sure on  the  toes,  which  causes  a 
corn  or  ingrowing  nail.  Have 
your  shoes  been  correct,  or  have 

they  been  too  loose  or  too  tight  ? 
.    J     ,.  ,.  FIG.  57.— ARCH  OF  FOOT. 

According  to  this  test,  what  pro- 
portion of  people  wear  shoes  that  are  too  tight  ?  6.  How  many 
sprained  ankles  have  you  known  among  boys ;  girls  ?  7.  Why  is  it 
that  people  who  grow  up  in  warm  climates  have  high,  arched  insteps, 
and  short,  elastic  feet,  but  people  of  the  same  race  who  pass  their  child- 
hood in  cold  climates  often  have  long  feet  with  low  arches  ? 

Instinct  as  a  Guide  for  using  the  Muscles.  — The  instinc- 
tive feeling  called  fatigue  tells  us  when  to  rest.  There  is 
also  a  restless,  uneasy  feeling  that  comes  over  a  natural, 
human  being  when  confinement  and  restraint  of  the  muscles 
have  reached  an  unhealthy  limit.  This  feeling  should  not 
be  repressed  for  long  at  a  time.  Many,  ruled  by  avarice, 
ambition,  interest  in  sedentary  work,  or  by  a  false  concep- 
tion of  duty,  have  repressed  this  feeling  and  have  lost  it. 
When  repeatedly  repressed,  it  is  lost,  and  the  person  has 
a  feeling  of  languor,  and  is  disinclined  to  the  very  activity 
that  his  health  demands. 

Exercise  and  Climate. — The  colder  the  climate,  the 
more  exercise  is  required  to  keep  the  body  in  perfect  con- 
dition, and  the  pleasanter  it  is  to  take  exercise.  English 
ladies  think  nothing  of  taking  a  ten-mile  walk  for  recrea- 
tion ;  but  this  would  be  too  much  in  many  parts  of  the 
United  States.  In  our  warmest  states  and  in  the  tropics, 
one  hour's  vigorous  physical  labor  a  day,  combined  with 
the  ordinary  activities  of  life,  will  keep  a  person  in  good 
condition ;  but  this  amount  is  absolutely  necessary,  for  if 
all  vigorous  exercise  is  omitted,  the  heat  causes  the  body 


68  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

to  become  so  relaxed,  and  the  organs  so  sluggish,  that 
sound  health  will  probably  be  lost.  In  the  colder  states, 
exercise  for  several  hours  is  needed  daily. 

Mental  and  Physical  Labor.  —  The  senseless  idea  that 
physical  labor  is  degrading,  has  led  to  the  ruin  of  the 
health  of  thousands.  No  truly  refined  person  can  enter- 
tain such  an  idea.  To  do  physical  labor  in  a  stupid  way 
is  a  disgrace.  An  example  of  this  is  a  farmer  that  works 
with  dull  tools,  and  leaves  his  implements  in  the  rain  to 
rust,  or  a  builder  that  does  not  build  well.  A  laborer  that 
never  reads  a  book  or  cultivates  his  mind  is  as  worthy  of 
respect  as  a  writer  or  professional  man  who  uses  his  mind 
only  and  neglects  his  body,  alloiving  his  muscles  to  dwindle, 
his  lungs  to  become  flattened,  his  digestive  canal  foul,  and 
his  tissues  impure. 

Complete  Living.  —  Numberless  people  have  devoted 
themselves  to  an  intellectual  occupation,  and  planned  to 
keep  their  bodies  sound  by  gymnastics  and  special  exer- 
cises. Because  of  the  monotony  of  exercises,  they  are 
soon  given  up  in  nearly  every  instance.  The  safest  way  is 
never  to  allow  all  the  energies  to  be  devoted  to  a  one-sided 
occupation,  but  so  to  plan  ones  life  and  work  that  a  part  of 
the  time  is  devoted  to  some  physical  work,  whether  it  be  in 
a  garden,  workshop,  or  orchard  ;  in  walking  a  long  distance 
to  the  office ;  at  bookbinding,  cooking,  wood  carving,  or 
any  one  of  various  other  useful  occupations.  The  result 
of  manual  training  shows  that  not  only  strength  of  body, 
but  strength  of  mind,  is  promoted  by  physical  labor.  It  may 
be  a  part  of  .the  secret  of  the  greatness  of  many  noted  men 
that  they  recognized  this  relation,  and  helped  the  mind 
to  do  its  best  by  taking  care  of  the  body.  Gladstone's 
favorite  exercise  was  wood  chopping,  and  he  possessed 
great  mental  strength  at  eighty  years  of  age ;  Peter  the 


THE  MUSCLES  69 

Great  worked  as  a  ship  carpenter  while  emperor ;  Franklin, 
the  great  scientist  and  statesman,  was  a  printer,  but  he 
neglected  exercise  and  became  gouty  when  old ;  George 
Washington  was  a  surveyor  and  farmer. 

Alcohol  and  Muscular  Strength.  —  Benjamin  Franklin, 
one  of  the  wisest  and  greatest  of  Americans,  was  a  printer 
when  he  was  a  young  man.  In  his  autobiography  he  gives 
an  account  of  his  experience  as  a  printer  in  London.  He 
says  :  "  I  drank  only  water ;  the  other  workmen,  fifteen  in 
number,  were  great  drinkers  of  beer.  On  occasion  I  car- 
ried up  and  down  stairs  a  large  form  of  types  in  each  hand, 
when  others  carried  but  one  in  both  hands.  They  won- 
dered to  see,  from  this  and  several  instances,  that  the 
Water-American,  as  they  called  me,  was  stronger  than 
themselves,  who  drank  strong  beer.  My  companion  at 
the  press  drank  every  day  a  pint  before  breakfast,  a  pint 
at  breakfast  with  his  bread  and  cheese,  a  pint  between 
breakfast  and  dinner,  a  pint  at  dinner,  a  pint  in  the  after- 
noon about  six  o'clock,  and  another  when  he  had  done  his 
day's  work.  I  thought  it  a  detestable  custom,  but  it  was 
necessary,  he  supposed,  to  drink  strong  beer  that  he  might 
be  strong  to  labor." 

EXERCISES  IN  WRITING.  —  The  Right  and  the  Wrong  Way  to  Ride 
a  Bicycle.  Write  a  Letter  to  a  Friend  who  has  begun  to  Drink.  Pay 
Day  at  a  Factory.  A  Graceful  Form :  how  Acquired ;  how  Lost. 

PRACTICAL  QUESTIONS.  —  1.  Can  we  always  control  the  voluntary 
muscles?  Do  we  shiver  with  the  voluntary  or  involuntary  muscles? 
2.  If  a  man  had  absolute  control  over  his  muscles  of  respiration, 
what  might  he  do  that  he  cannot  now  do?  3.  Why  is  one  who  uses 
alcoholic  drinks  not  likely  to  be  a  good  marksman?  4.  Why  should  a 
youth  who  wishes  to  excel  in  athletic  contests  abstain  from  the  use 
of  tobacco?  5.  Is  there  any  relation  between  the  amount  of  bodily 
exertion  necessary  for  a  person's  health  and  the  amount  of  wealth  he 
possesses?  6.  Can  you  relax  the  chewing  muscles  so  that  the  lower 


70  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

jaw  will  swing  loosely  when  the  head  is  shaken  ?  Can  you  relax  your 
arm  so  that  it  falls  like  a  rope  if  another  person  raises  it:  and  lets  it  fall? 
7.  The  average  man  has  sixty  pounds  of  muscle  and  two  pounds  of 
brain :  one  half  of  the  blood  goes  through  the  muscles  and  less  than 
one  fifth  goes  through  the  brain.  What  inference  may  you  draw  as  to 
the  kind  of  life  we  should  lead?  8.  Why  is  a  slow  walk  of  little  value 
as  exercise?  9.  How  can  we  best  prove  that  we  have  admiration  and 
respect  for  our  wonderful  bodies?  10.  Which  of  your  legs  do  you 
exert  more  in  walking?  (The  foot  on  that  side  is  larger,  as  shown  by 
the  fit  of  the  shoe.)  If  you  were  lost  on  a  prairie,  to  which  side  would 
you  turn  while  trying  to  go  straight?  11.  Show  that  physical  labor 
is  a  great  blessing.  Show  that  false  pride  causes  more  ill  health  than 
almost  anything  else.  Does  paleness  indicate  refinement  or  impure 
blood?  12.  If  fat  accumulates  at  the  waist  and  a  man  tries  to  restrain 
it  with  a  leather  belt,  or  a  woman  uses  a  corset,  why  do  the  abdominal 
walls  relax?  Why  does  the  fat  increase  still  faster?  What  would  be 
a  successful  way  of  diminishing  the  fat?  How  may  a  horse  be  prevented 
from  becoming  fat?  13.  Why  is  the  ability  to  relax  the  muscles 
thoroughly  of  great  benefit  to  the  health?  How  is  this  ability  tested? 
(Question  6.) 

KEY  TO  MUSCLE  CHART:  Plate  III,  Hie  Head.  Described  on 
Plate.  Plate  IV,  The  Trunk.  The  bowing  muscle  (sternomastoid} 
goes  from  behind  ear  to  breastbone;  see  5,  Fig.  63.  The  trapezius 
muscle  draws  head  and  shoulders  back  (attached  along  the  spine).  The 
shoulder-cap  muscle  (deltoid}  lifts  whole  arm  up  and  out.  Its  antago- 
nist (pectoralis)  draws  arm  down  and  in.  The  climbing  muscle  (latis- 
simus)  draws  arm  down  and  back.  The  pushing  muscle  (serratus) 
draws  shoulder  blade  forward.  The  straight  muscle  (rectus}  and  the 
external  and  internal  oblique  muscles  draw  the  abdominal  walls  in  and 
expel  the  breath.  The  standing  muscle  (glutens)  makes  body  erect 
after  stooping.  Plate  V,  The  Arm.  Fig.  66.  Biceps,  I,  bends  elbow; 
3,  4,  bends  fingers;  2,  5,  bends  wrist.  Fig.  67,  Triceps,  straightens 
elbow ;  extensors  straighten  thumb,  fingers,  and  wrist ;  ligament  binds 
tendons  down.  Plate  VI,  The  Leg  (front  view).  Fig.  68.  i,  4,  swings 
leg  outward ;  6,  swings  leg  inward ;  7,  straightens  knee ;  8,  5,  tailor's 
muscle  crosses  knee ;  2,  3,  9,  nerves  and  blood  vessels.  Fig.  69,  Tibi- 
alis,  raises  instep.  Extensors  straighten  toes.  Soleus,  see  Fig.  71. 
Ligament  binds  down  tendons.  Plate  VII.  Described  on  Plate. 

NOTICE  TO  TEACHER  AND  PUPILS  :  All  technical  names  in  above  key  are 
placed  in  parentheses  to  show  they  are  not  required.  They  are  for  aid  in 
referring  to  chart  and  for  the  most  advanced  classes  and  Schools  of  Physical 
Education. 


PLATE  II 


(70 


FIG.  60.  —  Desk  too  low.     (Jtgi.) 


FIG.  58.  — Improper  position; 
causes  spine  to  curve  to 
side;  raises  one  hip  and 
shoulder  above  the  other. 


FlG.  61.  — Correct  p 


FIG.  59.  —  Best  habitual  posi- 
tion ;  chest  is  free  to  ex- 
pand, and  weight  is  easily 
shifted  from  one  foot  to 
other. 


FlG.  62.  —  Slipping  down  in  seat. 


of  tlje 


CHART  OF  THE   MUSCLES 
In  five  plates  (after  Cunningham) 


PLATE  III.  —  THE  HEAD. 
PLATE  IV.  — THE  TRUNK. 
PLATE    V.— THE  ARM. 


PLATE    VI.— THE  LEG  (front  view). 
PLATE  VII.  —  THE  LEG  (rear  view). 


For  key  to  chart,  see  page  70.  The  positions  and  functions  of  the  muscles 
are  to  be  learned;  but  do  not  learn  their  names,  which  are  given  only  for 
reference. 


PLATE  III 
Moves  ear  (generally  useless) 


Scalp  muscle 
Raises  eyebrows 


Squints  eyes 
Used  in  frowning 

Compresses  nose 
i  Used  in  sneering 

Used  in  sneering 
Salivary  duct 
Puckers  mouth 
Used  in  smiling 
Used  in  blowing 
Used  in  scowling 
Used  in  grinning 

Closes  mouth 
Opens  mouth 


FIG.  63. —MUSCLES  OF  HEAD. 

I.  Lifts  car  (used  by  few).  2  Scalp  muscle  (used  by  few).  3.  Draws  back  ear  (used  by 
few).  4.  Throws  head  back.  5.  Turns  head  to  left,  or,  acting  with  its  partner,  bows 
the  head.  6.  Tendon  connecting  the  two  scalp  muscles. 


PLATE  IV 


FIG.  64.  —  MUSCLES  OF 
TRUNK  (rear  view). 


FIG.  65. —  MUSCLES  c 
TRUNK  (front  view). 


PLATE  V 


FIG.  66.  —  ARM  (front  view) . 

i,  2,  3.  4,  5.  Muscles. 

x'.  2'.  3  »   4',  5',  Tendons. 


FIG.  67.  — ARM  (seen  from  behind). 


BICEPS 


FG.66. 


Posterior 
ligament 
TENDON 

TENDOS 


FIG.  67. 


PLATE  VI 


Upper 
portion  of 
anterior 
annular 
ligament 


LIGAMENT 


FIG.  68. 


FIG.  69. 


PLATE  VII 


Great  sciatic 
nerve 


BICEPS  (long    Tii>ial 
head)  nerve  and 


BICEPS  (short 
head) 


Tibial  nerve 
BICEPS  TENDON 


OASTRO- 

CNEM1U8 


Internal) 

annular 
ligament 


FIG.  70.— MUSCLES  AT  BACK  OF  THIGH. 


FIG.  71.  —  MUSCLES  OF  CALF. 


Figs.  70,  71.  Biceps  bends  knee.  Gastrocnemius  (removed  in  Fig.  71)  draws  up  heel  and  raises  body 
upon  toes;  soleus  lies  beneath  it  and  has  the  same  function.  Both  muscles  are  attached  to  the 
tendon  of  Achilles,  the  largest  tendon  in  the  body. 


PLATE  VIII 

PHOTOMICROGRAPHS   (PEABODY) 
(Photographs  taken  through  a  microscope) 


FIG.  72.  —  SECTION  OF  SPINAL 
CORD,  showing  nerve  cells  (large 
black  spots)  with  their  branches 
(black  dots  and  lines).  Five 
bundles  of  nerve  fibers  are  shown 
near  upper  margin. 


FIG.  73.  — MUSCULAR  AND  OTHER 
LAYERS  IN  WALL  OF  STOMACH. 

i.  Mucous  lining.  2.  Layer  of  blood  vessels 
and  connective  tissue.  3.  Muscular  layer 
(involuntary  muscle).  4.  Connective 
tissue  fibers. 


FIG.  74. —YEAST  CELLS  (magnified  200 
diameters,  or  40,000  areas).  Yeast  cells 
change  sugar  into  alcohol  and  carbon- 
dioxid  gas. 


FIG.  75.  — LARGE  NERVE  TRUNK, 
such  as  supplies  the  muscles.  Cross 
sections  (magnified  6  diameters), 
showing  bundles  of  nerve  fibers. 


PLATE  IX 


PHOTOMICROGRAPHS   {Continued} 


OCfi 

•  c  ooa*£$xfd?jj 

"^QcZ    CC#~     ^^-CXrJ 

*_^^r^7 


FIG.  76.  —  HUMAN  BLOOD  CELLS 
(magnified  40,000  areas),  show- 
ing many  red  cells  and  a  single 
white  blood  cell  on  left  (larger 
than  red  cells) . 


FIG.  77.  — FROG'S  BLOOD  (magni- 
fied 2500  areas).  Red  cells  oval, 
nucleated,  and  larger  than  human 
blood  cells.  Nuclei  of  two  white 
cells  visible  near  center. 


FIG.  78.  —  CAPILLARIES  around 
air  sacs  of  lungs  (30  diameters). 
Air  sacs  in  white  spaces.  Dark 
lines  are  capillaries. 


FIG.  79.  —  CAPILLARIES  among  fibers 
of  voluntary  (cross  striped)  mus- 
cle. Compare  with  colored  Fig- 


CHAPTER  V 

THE  CIRCULATION 

The  Cells  have  a  Liquid  Home.  —  The  ameba,  one  of  the 
simplest  of  all  animals,  lives  under  water.  The  cells  in 
the  body  of  man,  the  highest  of  all  animals,  also  live  in  a 
watery  liquid.  This  liquid  is  called  lymph.  The  cells 
cannot  move  about  as  the  ameba  does  to  obtain  food,  so 
the  blood  brings  the  food  near  them  and  it  soaks  through 
the  blood  tubes  into  the  lymph.  As  the  water  in  a  sponge 
surrounds  every  fiber  of  the  sponge,  so  the  lymph  bathes 
every  cell  and  holds  the  food  ready  for  use  (see  colored 
Fig.  6).  The  ameba  gives  off  waste  material  into  the 
water ;  the  cells  of  the  body  give  it  off  into  the  lymph  to 
be  carried  off  by  the  circulation.  The  blood,  then,  has  two 
functions:  (i)  to  take  nourishment  to  the  tissues;  (2)  to 
take  away  waste  material  from  them. 

The  Organs  of  Circulation.  —  These  are  the  heart  (Fig. 
80),  which  propels  the  blood ;  the  arteries,  which  take 
blood  away  from  the  heart  (Plate  X);  the  veins,  which 
take  the  blood  back  to  the  heart ;  and  the  capillaries 
(Fig.  81),  which  take  the  blood  from  the  arteries  to  the 
veins.  See  the  author's  Flat  Manikin,  Plates  III,  IV. 

The  heart  (Fig.  80)  is  a  cone-shaped  organ  about  the 
size  of  its  owner's  fist.  It  lies  in  a  diagonal  position,  be- 
hind the  breastbone,  with  the  small  end  of  the  cone  ex- 
tending toward  the  left.  The  smaller  end  taps  the  chest 
wall  at  a  point  between  the  fifth  and  sixth  ribs  on  the  left 

79 


8o 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


FIG.  80.  — THE  HEART. 


side.  The  beat  of  the  heart  is  felt  most  plainly  at  this 
point,  and  this  has  given  rise  to  an  erroneous  belief 
that  the  heart  lies  on  the  left  side  of  the  body.  It  is 

almost  exactly  in  the  center  and 
lies  largely  behind  the  breastbone. 
Experiment  12.  Get  a  sheep's 
or  beef's  heart  from  the  butcher. 
Get  the  whole  heart,  not  simply 
the  ventricles  (as  usually  sold). 
Note  the  blood  vessels,  four  cham- 
bers, thickness  of  different  walls, 
valves,  cords,  openings. 

Why  the  Heart  is  Double.  - 
There  must  be  a  pump  to  receive 
the  impure  blood  from  the  body  and 
send  it  to  the  lungs  to  get  oxygen 
from  the  air,  and  there  must  be 
another  pump  to  send  the  pure  blood  from  the  lungs  back  to 
the  body.  Hence  there  are  two  pumps  bound  together  into 
one  heart,  beating  at  the  same  time  like  two  men  keeping 
step,  or,  like  two  carpenters  keeping 
time  with  their  hammers.  There 
are  valves  in  the  heart,  as  in  other 
pumps.  These  valves  are  so  arranged 
that  when  any  part  of  the  heart  con- 
tracts and  forces  the  blood  onward, 
the  blood  cannot  return  after  that 
part  of  the  heart  relaxes.  How  are 
the  pumps  placed  with  reference  to 
each  other?  Is  one  behind  the 
other  ?  Or  is  one  above  the  other  ?  No,  they  are  side 
by  side,  with  a  fleshy  partition  between  them  (Fig.  82). 
The  one  on  the  right  moves  the  impure  blood  from  the 


FIG.  81.  —  CAPILLARIES 
connecting  artery  (a) 
with  vein  £. 


THE   CIRCULATION 


81 


pulmonary 
veins 


body  to  the  lungs,  and  the  one  on  the  left  moves  the  pure 
blood  from  the  lungs  to  the  body.  There  is  no  direct 
connection  between  the  right  and  left  sides  of  the  heart. 
Each  pump  is  constructed  alike  and  has  the  same  parts. 

Each  pump  has  the  following  parts  (Fig.  82,  colored 
Fig.  10):  (i)  large  veins  bringing  the  blood;  (2)  a 
weak,  thin-walled  receiving  chamber  called  an  auricle  (see 
Fig.  82);  (3)  a  large  valve  situated  in  the  central  part 
of  the  heart,  leading  down  into  (4)  a  strong,  thick-walled 
sending  chamber  called  a  ventricle ;  (5)  a  large  artery 
leading  from  the  heart,  and  pro- 
vided with  a  valve,  so  that  the 
blood  cannot  flow  back.  The 
left  ventricle  has  thicker  walls 
than  the  right  ventricle 
(see  Fig.  82),  because  it 
must  send  the  blood  all 
over  the  body,  while  the  right 
ventricle  sends  the  blood  to  the 
lungs  which  surround  the  heart. 

To  trace  one  complete  circuit 
of  the  blood  (see  colored  Fig.  i), 
let  us  begin  with  the  blood  in 
the  capillaries  of  the  outer  tis- 
sues, such  as  the  skin  or  mus- 
cles. The  blood  goes  through  FlG-  82. -DIAGRAM  OF  HEART. 

.           .  Notice  the  two  dark  spots  in  the  right  auri- 

Small     VdnS     Which     Unite     mtO  cles.  and  four  dark  spots  in  left  auri- 

.                      .           ,                11-1  c'es  where  the  veins  enter.      Does  the 

tWO   large   VetnS  through   Which  aorta  pass  in  front  of,  or  behind,  the 

it  enters  the  right  auricle,  goes      pulmonary  artery  ? 
through  the  tricuspid  valve  into  the  right  ventricle,  then 
through  a  semilunar  valve  into  the  pulmonary  artery  lead- 
ing to  the  lungs.    Becoming  purified  while  passing  through 
the  capillaries  of  the  lungs t  the  blood  goes  through  the 


puilmonarj 
veins 


82  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

pulmonary  veins  to  the  left  auricle,  then  through  the 
bicuspid,  or  mitral  valve,  to  the  left  ventricle,  whence  it  is 
forced  through  a  semilunar  valve  into  the  largest  artery  of 
the  body,  called  the  great  aorta.  Thence  it  goes  to  the 
smaller  arteries,  and  then  to  the  capillaries  of  the  tissues 
in  general,  thus  completing  the  circuit. 

Seen  under  the  microscope  the  arteries  and  veins  show 
that  they  are  made  of  three  kinds  of  tissues  arranged  in 
three  coats  (Fig.  83):  a  tissue  resembling  epithelial  tissue 
(see  p.  12),  as  a  lining  to  prevent  friction  ;  connective  tissue 
(see  p.  1 1),  to  give  elasticity  ;  and  muscular  tissue  (see  p.  9), 
to  enable  the  vessels  to  change  in  size.  Let  us  inquire  why 
blood  vessels  must  have  these  three  properties. 

Why  the  Blood  Vessels  must  be  Elastic.  —  The  aorta  and 
its  branches  are  always  full  of  blood.  When  the  left 
ventricle  with  its  strong,  muscular  walls  contracts  (Fig. 
82),  the  blood  in  the  aorta  and  small  blood  tubes  cannot 
move  forward  fast  enough  to  make  room  for  the  new  supply 
so  suddenly  sent  out  of  the  ventricle.  Where  can  this  blood 
go  ?  If  a  cup  is  full,  it  cannot  become  more  full ;  not  so 
with  an  artery.  The  elastic  connective  tissue  allows  it  to 
expand  as  a  rubber  hose  does  under  pressure.  The  first 
part  of  the  aorta  having  expanded  to  receive  the  incoming 
blood,  the  stretched  elastic  walls  contract  and  force  blood 
into  the  portion  of  the  aorta  just  ahead,  forcing  it  to  ex- 
pand in  turn.  Thus  a  wave  of  expansion  travels  along  the 
arteries.  This  wave  is  called  the  pulse. 

The  pulse  may  be  most  easily  felt  in  the  wrists  and  neck. 
As  the  artery  stretches  and  springs  back,  one  beat  of  the 
pulse  is  felt.  In  men  there  are  about  seventy  heart  beats 
or  pulse-beats  a  minute.  In  women  the  rate  is  about  eighty 
a  minute.  It  is  slowest  when  one  is  lying  down,  faster 
while  sitting,  still  faster  when  standing,  and  fastest  of  all 


THE   CIRCULATION 


during  running  or  other  violent  exercise.  You  should  not 
think  that  the  muscular  or  middle  layer  of  the  artery 
actively  contracts  and  helps  to  send  along  the  pulse  wave ; 
for  this  wave  is  simply  the  passive  stretching  and  contract- 
ing of  the  elastic  tissue,  and  travels  like  a  wave  passing  a 
pond  when*  a  stone  is  dropped  into  the  water.  The  force 
of  the  pulse  is  furnished,  not  by  the  muscle  fibers  in  the 
artery,  but  by  the  heart ;  the  outer, 
or  connective  tissue,  coat  enables 
the  pulse  to  travel.  You  have  yet 
to  learn  the  purpose  of  the  muscu- 
lar layer  in  the  arterial  wall. 

Why  and  how  the  Blood  Vessels 
vary  in  Size  from  Time  to  Time.  — 
The  body  of  an  adult  contains  about 
five  quarts  of  blood.  You  have 
learned  that  the  blood  furnishes 
the  nourishment  needed  for  the 
activity  of  each  organ.  The  more 
vigorous  the  work  of  any  organ,  the 
greater  is  the  amount  of  blood 
needed.  The  whole  amount  of  blood  ^ 

in  the  body  cannot  be  suddenly  in- 

Fi 0.83.— SECTION  OF  ARTERY, 
creased,  but  the  muscular  coat  of  the       A,  AND  VEIN,  v,  showing 

arteries  going  to  the  working  organ  inner  coat'  '  (endothelial> : 
relaxes,  and  the  arteries  are  enlarged 
by  the  pressure  from  the  heart.  Con- 
sequently, more  blood  goes  to  the  active  organ,  and  the 
other  organs  get  along  with  less  blood  for  the  time.  When 
we  are  studying,  our  brains  get  more  blood  ;  when  running, 
the  leg  muscles  get  more ;  after  a  hearty  dinner,  the  stom- 
ach and  intestines  get  more  than  any  other  part  of  the 
body.  Why  is  it  difficult  to  do  the  best  studying  and 


middle  coat,  m  (muscular) ; 
and  third  coat,  a  (connective 
tissue) . 


84 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


digest  a  meal  at  the  same  time  ?  We  see  that  the  muscular 
coat  of  the  arteries  is  a  very  useful  coat,  for  it  enables  the 
supply  of  blood  to  be  increased  in  any  organ  which  is  in 
special  need  of  it.  Without  these  muscles,  all  parts  would 
receive  blood  equally  at  all  times,  whether  they  needed  it  or 
not.  With  these  muscles  the  particular  amount  of  blood  that 
flows  to  each  organ  may  be  modified.  When  all  the  organs 
need  a  greater  supply  of  fresh  blood  at  the  same  time  the 
demand  can  be  met  only  by  the  heart  beating  faster  and 
stronger.'  When  all  the  organs  need  less  blood  the  heart 
beats  more  slowly,  as  during  sleep. 

Why  the  Blood  Vessels  must  be  Smooth.  —  The  inner 
coat  of  the  heart  and  other  blood  vessels  is  made  of  tissue 
like  the  epithelial  tissue  which  forms  the  epidermis  and  the 

smooth  lining  of  the  mouth  and 
other  organs.  The  purpose  of  this 
tissue  is  to  lessen  friction,  and  thus 
save  the  work  of  the  heart.  The 
friction  is  greatest  in  the  capil- 
laries because  of  their  small  size. 
The  inner  coat  of  smooth  cells  is 
the  only  coat  that  is  prolonged  to 
form  the  capillaries  (see  Fig.  84). 

The  capillaries  are  small,  thin, 
short,  and  very  numerous.  They 
are  very  small  so  that  they  may  go 
in  between  the  cells  of  the  tissues 
(colored  Figs.  6  and  12).  The  capil- 
laries are  very  thin  so  that  the 
nourishment  from  the  blood  may  pass  readily  into  the 
tissues,  and  the  waste  material  pass  readily  into  the  blood. 
They  are  very  short  so  that  the  friction  may  be  less  ;  and 
they  are  very  numerous  so  that  all  parts  of  the  tissues  may 


FIG.  84.  — CELLS  forming  the' 
walls  of  capillaries.  Notice 
that  each  cell  has  a  nucleus 
and  three  branches. 


THE   CIRCULATION  85 

be  supplied  with  blood,  and  that  the  blood  may  flow  very 
slowly  through  them.  Because  of  the  number  of  the  capil- 
laries, their  total  volume  is  several  hundred  times  larger 
than  the  volume  of  the  arteries  that  empty  into  them, 
or  of  the  veins  {hat  flow  from  them.  Hence  the  blood 
flows  slowly  through  the  capillaries,  as  water  flows  slowly 
through  a  lake  along  the  course  of  a  river.  All  the  changes 
between  the  blood  and  the  lungs,  and  between  the  blood 
and  the  tissues,  take  place  in  the  capillaries,  and  the  object 
of  the  other  parts  of  the  circulation  is  merely  to  move 
the  blood  continually  through  the  capillaries  (see  colored 
Figs.  7  and  8). 

The  veins  have  very  thin,  soft  walls  in  comparison  to  the 
arteries.  There  is  no  pulse  in  the  veins,  and  the  pressure 
due  to  the  heart  beat  is  very  slight  in  the  veins.  There 
are  other  aids  to  the  flow  of  blood  in  the  veins  which  we 
shall  soon  study. 

The  effect  of  gravity  is  to  retard  the  flow  in  certain  parts 
of  the  body  and  aid  the  flow  in  other  parts,  according  to 
the  position  of  the  body. 

Experiment  13.  Hold  the  right  hand  above  the  head  for 
a  few  minutes.  At  the  same  time  let  the  left  hand  hang 
straight  down.  Then  bring  the  hands  together  and  see 
which  is  of  a  darker  red  because  of  containing  more  blood. 
Now  reverse  the  position  of  the  hands  for  a  few  minutes, 
and  find  whether  the  effect  is  reversed.  The  downward 
flow  of  blood  is  aided  by  the  weight  of  the  blood,  and  the  up- 
ward pressure  is  retarded  by  it.  Garters  compress  the  soft, 
thin  walls  of  the  veins  more  than  the  thick  walls  of  the  ar- 
teries, and  serve  to  retain  the  blood  below  the  knee.  As 
the  return  flow  is  also  hindered  by  the  weight  of  the  blood, 
varicose  veins,  which  are  veins  permanently  enlarged,  occur 
below  the  knee  oftener  than  in  any  other  part  of  the  body. 


86  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

Fainting  is  usually  due  to  lack  of  blood  in  the  brains 
which  in  turn  results  from  a  weakening  of  the  heart  beat. 
Since  the  brain  cannot  work  without  fresh  blood,  fainting 
is  accompanied  by  unconsciousness.  Recovery  from  faint- 
ing is  aided  by  loosening  the  clothing  at  the  neck  and  by 
placing  the  head  of  the  patient  a  little  lower  than  the  body 
so  that  the  weight  of  the  blood  may  aid  the  flow  to  the 
brain.  Dashing  a  little  cold  water  in  the  face  shocks 
the  nerves  and  arouses  the  heart  to  stronger  beats. 

Observations  on  the  Blood  Flow  in  the  Veins.  —  Place  the 
tip  of  the  middle  finger  on  one  of  the  large  veins  of  the 
wrist ;  with  the  forefinger  then  stroke  the  vein  toward 
the  elbow  so  as  to  push  the  blood  from  a  portion  of  it, 
keeping  the  fingers  in  place.  The  vein  remains  empty 
between  the  fingers.  Lift  the  finger  nearer  the  heart  and 
no  blood  enters  the  vein  ;  there  is  a  valve  above  whicJi  holds 
it  back.  Lift  the  other  finger  and  the  vein  fills  instantly. 
Stroke  a  vein  toward  the  hand,  and  notice  that  the  blood 
causes  the  veins  to  swell  up  into  little  knots  where  the 
valves  are.  (Experiments  upon  veins  are  plainest  with 
adults  whose  veins  are  large.)  The  veins  have  valves 
placed  frequently  along  their  course  (Fig.  85).  These 
valves  are  pockets  made  by  a  fold  in  the  inner  coat  of 
the  wall  of  the  vein.  When  a  boy  places  his  hand  in  his 
pocket,  the  pocket  swells  out ;  but  if  he  rubs  his  hand  on 
the  outside  of  the  pocket  from  the  bottom  toward  the  top, 
it  flattens  down.  So  with  the  action  of  the  blood  upon 
the  valves  in  the  veins. 

How  Muscular  Exercise  aids  the  Heart.  —  When  a  muscle 
contracts  it  hardens  and  presses  upon  a  vein  which  goes 
through  the  muscle,  and  the  blood  is  pressed  out  of  the  vein 
(see  Fig.  85).  The  blood  cannot  go  toward  the  capillaries, 
for  the  valves  fill  and  close  when  it  starts  that  way ;  so  it 


THE    CIRCULATION 


all  must  go  out  toward  the  heart.  When  the  muscle  relaxes, 
the  blood  that  has  been  pressed  forward  cannot  go  back 
because  of  the  valves,  but  the  valves  nearer  the  capillaries 
open,  and  the  veins  are  filled  from  the  capillaries  (Fig.  81). 
When  the  muscle  contracts  again,  the  same  effect  on  the 
blood  movement  is  repeated.  We  see,  therefore,  that  every 
contracting  muscle  converts  into  a  pump  the  vein  running 


FlG.  85.  —  Showing  valves  in  veins.     (Jegi.) 

through  it,  and  when  a  person  works  or  exercises,  many 
little  pumps  are  working  all  over  the  body,  aiding  the 
heart  in  its  function.  This  aid  makes  the  blood  flow 
faster  and  relieves  the  heart  of  part  of  its  work,  so  that 
it  beats  faster,  just  as  a  horse  might  trot  faster  if  another 
horse  helped  to  draw  the  load.  Why  does  the  pressure  of 
a  contracting  muscle  upon  an  artery  not  aid  the  blood  flow 
in  the  artery  ? 

How  Breathing  aids  the  Heart.  —  Breathing  is  a  blood- 
pumping  process  as  well  as  an  air-renewing  process.  When 
the  chest  expands,  blood  is  drawn  into  it.  When  the  chest 
contracts,  the  flow  of  blood  away  from  it  is  aided.  As  the 
chest  expands,  the  downward  pressure  of  that  great,  broad 
muscle,  the  diaphragm  (Fig.  96),  compresses  the  liver, 


88 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


stomach,  and  other  abdominal  organs,  and  forces  the 
venous  blood  upward  into  the  expanding  chest,  thus 
helping  it  on  its  way  to  the  heart.  But  if  the  abdominal 
wall  is  weakened  by  tight  lacing  or  by  the  pressure  of 
belts  and  bands  which  support  the  clothing,  the  weak 
abdominal  wall  yields  to  the  downward  pressure  of  the 
diaphragm,  and  no  compression  of  the  liver  or  aid  to  the 
circulation  will  result. 

How  to  strengthen  the  Heart. — The  heart  is  a  muscle, 
and  the  muscles  of  an  idle  man,  or  an  exclusive  brain 
worker,  lose  strength.  The  heart  may 
be  made  strong  by  exercise,  as  may  any 
other  muscle.  The  same  exercise  which 
strengthens  the  arms  and  legs  strengthens 
the  heart  also  by  compelling  it  to  work 
more  in  order  that  the  other  muscles 
may  have  enough  fresh  blood.  One  who 
has  neglected  physical  exercise  should 
take  it  up  gradually,  and  avoid  causing 
the  heart  to  palpitate  with  unpleasant 
strength.  When  the  heart  has  been 
excited  by  exercise,  the  pulse  should 
return  to  its  normal  rate  after  a  few 
minutes  of  rest  if  the  exercise  has  not  been  excessive. 
How  the  Blood  Vessels  are  Controlled.  —  Evidently  the 
blood  vessels  are  not  regulated  by  the  will.  We  cannot 
voluntarily  increase  the  beating  of  the  heart,  or  cause  it  to 
slacken  its  action.  Even  an  actor  cannot  cause  his  face 
to  turn  pale  or  to  blush  at  will.  This  is  because  the  tiny 
muscles  in  the  walls  of  the  blood  vessels  are  involuntary 
muscles.  They  are  controlled  by  nerves  (the  sympathetic 
nerves)  which  are  not  subject  to  the  will  (see  Fig.  156). 
The  nerve  center  which  controls  the  blood  vessels  is 


FIG.  86.  —  The  ventri- 
cles of  a  dog's  heart 
relaxed  (above) ,  and 
contracted  (below). 


THE  CIRCULATION  89 

located  in  the  top  of  the  spinal  cord  at  the  base  of  the 
brain.  When  cold  air  strikes  the  skin,  the  nerves  near 
the  arteries  are  stimulated,  the  arteries  in  the  skin  con- 
tract, and  the  skin  turns  white.  When  the  heat  from  a  hot 
fire  strikes  the  skin,  the  nerves  are  soothed,  the  arteries 
relax,  and  the  face  becomes  red.  When  the  stomach  is 
burdened  with  food,  the  heart  beats  faster  and  sends  more 
blood  to  aid  in  digestion.  When  we  run  fast,  the  heart 
beats  fast  to  supply  more  blood  to  the  muscles,  but  it 
slows  down  as  sleep  comes  on,  that  the  body  and  brain 
may  rest. 

There  are  Two  Kinds  of  Nerves  that  affect  the  Heart.  — 
One  kind,  called  the  sympathetic  nerves,  brings  impulses 
which  increase  its  action.  Another  kind,  the  two  vagus 
nerves,  serves  to  decrease  the  action  of  the  heart  (see  col- 
ored Fig.  1 6).  This  pair  of  nerves  comes  directly  from 
the  brain  ;  the  sympathetic  nerves  do  not  (see  syy  colored 
Fig.  16). 

How  the  Heart  is  Nourished.  —  The  heart  has  a  smooth, 
sleek  lining  which  will  not  absorb  food  from  the  blood. 
Therefore,  the  heart  does  not  get  food  from  the  blood  that 
fills  its  chambers ;  but  the  first  artery  which  branches  from 
the  aorta  goes  down  into  the  walls  of  the  heart  to  carry 
nourishment  to  it. 

THOUGHT  QUESTIONS.  —  The  Complexion.  1.  Check  words  which 
describe  a  healthy  skin  :  hard,  soft,  dry,  moist,  flexible,  elastic,  stiff,  firm, 
flabby,  smooth,  dingy,  rough,  pink,  yellow,  pale,  velvety.  2.  What  is 
the  best  means  of  improving  the  color  of  the  skin  ?  The  worst  means  ? 
3.  Is  a  "white  lie"  less  deceptive  than  a  pink  one  ?  4.  What  unde- 
sirable qualities  (Question  i)  do  dry  powders,  hot  winds,  and  overheated 
rooms  give  to  the  skin  ?  Why  is  their  effect  the  same  ?  5.  Think 
of  five  girls  under  twelve  years  of  age,  and  five  grown  young  ladies. 
How  many  of  each  have  smooth,  rosy  complexions  ?  Dingy,  bad  com- 
plexions ?  6.  Pimples  are  caused  by  germs.  Why  does  thorough  and 
frequent  washing  of  the  face  tend  to  prevent  them  ?  7.  Why  does 


QO  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

thorough  washing  each  day,  followed  by  prolonged  and  vigorous  rub- 
bing with  a  towel,  make  the  skin  smooth,  pink,  and  velvety  ?  8.  Why 
does  neglect  to  rub  the  face  after  washing  it,  and  the  use  of  face  pow- 
ders, cause  blackheads,  and  make  the  skin  flabby,  dark,  and  rough  ? 
9.  Is  a  powdered  face  or  a  clean  face  more  agreeable  to  a  refined  per- 
son ?  10.  Why  does  eating  too  much  and  working  too  little  cause  a 
bad  complexion  ?  11.  Show  how  ignorant  treatment  of  the  complexion 
causes  many  ladies  to  appear  older  or  less  healthy  than  they  really  are  ? 
Experiment  14.  Fine  dry  powder  is  one  of  the  most  powerful  means 
of  extracting  moisture.  Moisten  two  pieces  of  leather.  Apply  face 
powder  to  one  and  place  the  other  in  the  sun.  Which  piece  dries  first  ? 

The  Blood  which  flows  from  a  cut  finger  seems  to  be  a 
bright  red  throughout.  When  a  drop  of  it  is  looked  at 
through  a  microscope,  however,  the  liquid  itself  is  seen  to  be 
almost  as  clear  as  water.  This  liquid  is  called  the  plasma. 
By  means  of  the  microscope  the  red  color  of  the  blood  is 
seen  to  be  produced  by  millions  of  round  red  disks,  floating 
about  in  it.  The  disks  are  called  red  corpuscles  (Fig.  76). 
By  patient  search,  a  few  irregularly  shaped  bodies,  almost 
transparent,  and  called  white  corpuscles,  may  be  found. 
The  red  corpuscles  go  only  where  the  plasma  carries  them. 
The  white  corpuscles  sometimes  leave  the  blood  vessels 
entirely.  At  times  one  may  be  seen  shaped  like  a  dumb- 
bell, half  of  it  through  the  wall  of  the  blood  vessel,  and 
half  still  in  the  blood  vessel.  After  the  corpuscle  is  out,  no 
hole  can  be  found  to  account  for  its  mysterious  passage. 

Experiments.  — 15.  Examine  a  drop  of  blood  under  the 
microscope,  first  diluting  it  with  a  little  saliva.  16.  Wrap 
a  small  frog  in  a  moist  cloth,  lay  on  a  piece  of  glass,  place 
under  the  microscope,  and  study  the  circulation  in  the  web 
of  its  foot. 

The  Use  of  Each  Part  of  the  Blood.  —  ^\\Q  plasma  keeps 
the  blood  in  a  liquid  state,  so  that  it  may  flow  readily ;  the 
plasma  also  transports  the  food  that  has  been  eaten  and 
digested,  and  carries  away  waste  material  to  the  kidneys. 


THE   CIRCULATION 


FIG.  87.—  BLOOD  CORPUSCLES. 

Bt  red  c-lls  seen  from  the  side ;  D,  red  cells  seen 
on  edge ;  gtft  white  blood  cells. 


The  red  corpuscles  transport  the  oxygen  from  the  lungs  to 
the  tissues.  The  white  corpuscles  devour  and  destroy  irri- 
tating particles  such  as^drugs,  poisons,  and  germs.  They 
are  of  great  importance  in  purifying  the  blood  and  as  a  pro- 
tection against  disease 
(Fig.  87). 

The  Pulmonary  and 
the  Systemic  Circula- 
tions. —  Each  of  these 
is  really  only  a  part  of 
the  general  circulation. 
The  blood  vessels  which 
lead  the  blood  from  the 
heart  to,  through,  and 
from  the  lungs  consti- 
tute the  so-called  pulmonary  circulation.  The  vessels 
which  lead  the  blood  from  the  heart  to,  through,  and  from 
the  other  organs  constitute  the  systemic  circulation. 

Incorrectness  of  the  Terms  "Arterial"  and  "Venous 
Blood."  By  venous  blood  is  usually  meant  impure  blood, 
but  the  blood  in  the  pulmonary  veins  is  not  impure,  having 
just  been  purified  in  the  lungs.  By  arterial  blood  is  usually 
meant  pure  blood ;  but  blood  in  the  pulmonary  artery  is  on 
its  way  to  the  lungs  to  be  purified.  Hence  arterial  blood 
is  not  always  carried  in  artei  ies,  nor  venous  blood  in  the 
veins.  The  terms  are  appropriate  only  when  applied  to 
the  systemic  portion  of  the  circulation.  Oxygenated  blood 
and  deoxygenated  blood  would  be  correct  expressions. 

The  Three  Purifications  of  the  Blood. 

Portal  Circulation.  When  the  blood  is  forced  out  by  the 
heart,  the  part  that  goes  to  the  stomach  and  intestines 
where  the  food  is  absorbed  is  gathered  up  by  a  large  vein, 
called  the  portal  vein,  and  carried  to  the  liver.  In  the 


92  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

liver  the  blood  is  purified  by  impurities  being  burned  up 
and  changed  into  bile.  The  blood  is  then  carried  from  the 
liver  to  the  heart  by  a  large  vein.  See  colored  Figure  3, 
showing  the  circulation  of  the  blood  among  the  liver  cells. 

Renal  Circulation.  Two  other  branches  from  the  aorta 
carry  blood  to  the  kidneys.  There  the  urea  and  a  large 
amount  of  water  are  taken  out,  and  the  purified  blood  is 
emptied  into  the  large  vein  that  leads  up  to  the  heart. 
See  colored  Figure  2,  Plate  X. 

Pulmonary  Circulation.  This  is  the  circulation  through 
the  lungs  and  has  already  been  described.  This  circulation 
removes  carbon  dioxid  gas  from  the  blood.  Some  impuri- 
ties escape  from  the  blood  through  the  skin.  See  diagram 
of  an  air  cell  in  lungs,  colored  Figure  7. 

Coagulation.  — So  long  as  blood  is  in  an  uninjured  blood 
vessel  it  remains  a  liquid.  In  a  few  minutes  after  it 
escapes  from  a  vessel,  it  forms  into  a 
stiff,  jellylike  mass  called  a  clot.  The 
process  of  forming  the  clot  is  called 
coagulation,  and  it  is  brought  about  by 
albumin  which  is  always  in  the  plasma 
of  healthy  blood.  The  albumin  forms 
into  a  network  of  fine  threads  through- 
FIG.  88.  — BLOOD  CI.OT  out  the  mass,  and  the  corpuscles  become 

separated  troin  serum.  11-^1  i  -r,,          ,    . 

entangled  in  the  meshes.  The  clot  con- 
sists of  the  albumin  and  corpuscles ;  the  watery  portion  of 
the  blood,  called  the  serum,  separates  from  the  clot  (Fig. 
88).  The  property  of  coagulating  is  of  great  value  in  sav- 
ing life,  as  the  clot  often  plugs  up  a  cut  blood  vessel. 

Veins  and  Arteries  Compared.  —  The  veins  have  soft 
walls  and  the  arteries  have  elastic  walls.  When  a  vein  is 
cut,  it  may  usually  be  closed  by  pinching  the  walls  of  the 
end  together.  If  an  artery  is  cut,  the  walls  will  not  readily 


THE   CIRCULATION  93 

stick  together,  but  often  stand  open  until  the  end  of  the 
artery  is  tied.  For  this  reason,  and  because  an  artery  is 
subject  to  the  direct  pressure  of  the  heart,  a  cut  artery  is 
more  dangerous  to  life  than  a  cut  vein.  Because  of  the 
toughness  of  the  arteries,  and  because  they  are  located  close 
tc  the  bones,  they  are  less  \ikely  to  be  cut  than  the  veins, 
which  are  softer  and  nearer  the  surface.  A  cut  artery  may 
be  known  from  a  cut  vein  by  the  brighter  color  of  the  blood, 
and  by  the  flow  being  stronger  at  each  heart  beat,  while  the 
flow  from  a  vein  is  uniform.  Pressure  to  stop  the  flow  of 
blood  from  an  artery  should  be  applied  between  the  cut  and 
the  heart ;  but  when  the  blood  comes  from  a  vein  the  presr 
sure  should  be  applied  to  the  side  of  the  cut  farthest  from 
the  heart.  The  veins  empty  into  the  auricles ;  the  arteries 
lead  from  the  ventricles ;  and  there  is  a  semilunar  valve  at 
the  origin  of  each  artery. 

THE   LYMPHATIC   SYSTEM 

This  system  contains  the  lymph.  It  consists  of  lymph 
spaces,  lymph  tubes,  and  lymphatic  glands.  Lymph  cor- 
responds nearly  to  the  blood  without  the  red  corpuscles.  You 
have  often  seen  it  in  a  blister,  or  oozing  out  where  the  skin 
has  been  grazed  without  breaking  a  blood  vessel. 

Necessity  for  Lymph  Spaces. — The  body  cannot  be 
nourished  with  the  albumin,  sugar,  oxygen,  and  other 
things  carried  by  the  blood,  until  this  food  passes  out  of 
the  blood  vessels.  The  food  leaves  the  blood  through  the 
thin  walls  of  the  capillaries.  Many  of  the  cells  do  not 
touch  the  capillaries,  and  the  lymph  penetrates  the  spaces 
between  the  cells  to  reach  them  (see  colored  Fig.  6).  If 
there  were  no  lymph  spaces,  these  cells  could  not  get  any 
food.  The  lymph  bathes  the  cells,  and  the  cells  absorb 


94  LESSORS  IN  HYGIENIC  PHYSIOLOGY 

what  they  want  from  the  nourishing  fluid.  The  red  corpus- 
cles bearing  the  oxygen  cannot  pass  through  the  capillary 
walls.  Oxygen,  being  a  gas,  readily  passes  through  the 
walls  and  reaches  the  cells  through  the  lymph  in  the 
lymph  spaces.  Carbon  dioxid  passes  back  through 
the  capillary  walls  directly  into  the  blood  and  is  taken  to 
the  lungs.  You  will  soon  learn  what  becomes  of  the  other 
waste  materials. 

Need  of  Lymphatics.  — If  when  the  plasma  passes  into  the 
tissues  none  of  it  returned  to  the  blood  vessels,  the  blood 
would  soon  become  thick  for  want  of  the  liquid  plasma,  and 
the  tissues  would  be  swollen.  Very  little  of  the  lymph  can 
soak  back  directly  into  the  blood  tubes  because  of  the 
greater  pressure  in  the  blood  tubes,  brought  about  by  the 
heart's  continual  pumping.  The  lymph  contains  waste 
material,  which  must  be  removed,  and  much  unused  food 
which  nature,  like  an  economical  housekeeper,  will  offer 
to  the  tissues  again.  The  vessels  that  take  the  lymph  back 
into  the  blood  are  called  lymphatics.  See  Fig.  90. 

The  Lymphatic  Circulation  (Fig.  89).  —  The  lymph 
flow,  unlike  the  blood  flow,  begins  at  a  certain  place  and 
ends  at  another  certain  place.  The  blood  flow,  on  the 
contrary,  does  not  begin  nor  end,  but  makes  a  never 
ending  circle.  The  countless  lymphatics  begin,  with  open 
ends,  in  the  lymph  spaces  between  the  cells  (colored 
Fig.  6).  Smaller  lymphatics  unite  to  form  larger  ones 
until  finally  they  all  unite  into  two  large  ones  that  empty 
into  two  large  veins  under  the  collar  bones,  near  the  neck. 
The  one  that  empties  under  the  left  collar  bone  is  the 
largest  lymphatic  in  the  body,  being  about  the  size  of  a 
goose  quill.  It  is  called  the  thoracic  duct  because  it  goes 
up  through  the  thorax  just  in  front  of  the  spinal  column 
(colored  Fig.  15).  The  other  large  lymphatic  at  the  neck 


THE   CIRCULATION 


95 


FIG.  89.  — THE  LYMPHATIC  SYSTEM, 
showing  the  lymphatics,  the  glands 
in  the  groins  and  armpits,  the  lac- 
teals  which  absorb  the  fat  from  the 
intestine,  and  the  thoracic  and  right 
lymphatic  ducts  emptying  into  veins 
near  the  neck.  (Compare  with  col- 
ored Figure  15.)  The  small  diagram 
shows  the  two  parts  of  the  boily 
drained  by  the  two  ducts. 


is  called  the  right  lymphatic 
duct  (colored  Fig.  15).  It 
receives  lymph  from  the 
lymphatics  that  drain  the 
right  side  of  the  head, 
neck,  and  chest,  and  the 
right  arm  (see  Fig.  89). 
The  thoracic  duct  receives 
the  lymph  from  all  the  rest 
of  the  body.  See  smaller 
diagram  of  Figure  89. 

In  persons  with  the 
dropsy,  the  lymph  accumu- 
lates in  the  lymph  spaces 
and  is  not  drained  away  by 
the  lymph  flow.  Farmers 
often  drain  marshy  land 
with  underground  pipes  or 
tiles;  if  the  tiles  fail  to 
work,  the  land  becomes 
very  wet  and  soggy.  The 
tissues  of  a  person  with 
dropsy  may  be  compared  to 
such  land.  As  in  such 
land,  the  lowest  part  would 
become  soggy  first,  so 
dropsy  usually  shows  itself 
first  by  swelling  of  the  feet 
and  the  leg  below  the  knee. 

There  is  a  set  of  lym- 
phatics called  lacteals,  situ- 
ated in  the  abdomen,  which 
have  the  function  of  absorb- 


96  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

ing  digested  fats  from  the^intestine  (see  colored  Fig.  15, 
Fig.  89,  also  p.  161). 

What  makes  the  Lymph  Flow  ?  —  The  heart  does  not, 
for  its  pressure  is  not  transmitted  beyond  the  blood  tubes. 
There  is  no  lymph  heart,  for  every  minute  part  of  the 
body  has  been  dissected  numberless  times,  and  no  pumps 
have  been  found  except  those  in  the  heart.  It  would  not 
be  possible  to  cause  the  lymph  to  flow  if  it  were  not  for 
the  valves  in  the  lymphatics.  These  are  so  numerous  that 
a  lymphatic  has  a  beaded  appearance ;  they  all  open  the 
same  way  (see  colored  Fig.  13).  Hence  the  successive 


FIG.  90.— SURFACE  LYMPHATICS  OF  HAND. 


pressures  of  a  working  tmiscle  move  the  lymph  forward  in 
the  lymphatics  in  the  same  way  that  the  blood  is  moved 
forward  in  the  veins  (p.  87).  Likewise,  if  the  body  is 
pressed  upon  or  shaken,  as  when  riding  a  trotting  horse,  or 
in  a  jolting  vehicle,  the  lymph  is  moved  beyond  the  valves 
at  every  jolt.  This  aids  the  muscles  in  causing  the  lymph 
to  circulate.  Without  exercise  the  lymph  stagnates,  and 
the  body  becomes  poisoned  by  its  own  wastes.  When,  by 
exercise,  the  lymph  is  promptly  returned  to  the  blood, 
poisonous  waste  materials  are  removed,  and  do  not  inter- 
fere with  the  free,  healthy  life  of  the  cells. 


THE   CIRCULATION  97 

The  Lymphatic  Glands  and  their  Use  (colored  Fig.  13). 
-These  glands  are  kernel-like  enlargements  along  the 
lymphatics,  and  they  contain  a  great  many  lymph  cells, 
which  purify  the  lymph  as  it  passes  through  them.  The 
lymphatic  glands  are  especially  numerous  in  the  armpits 
and  the  groins  (see  Fig.  89).  The  cells  in  the  lymph 
glands  multiply,  and  some  of  them  are  carried  by  the 
lymph  into  the  blood  to  become  those  remarkable  little 
bodies,  the  white  corpuscles. 

The  spleen  is  located  just  under  the  diaphragm,  at  the 
left  of  the  stomach ;  its  color  is  purplish  red.  By  some 
physiologists  it  is  classed  with  the  lymph  glands.  If  the 
white  corpuscles  may  be  compared  to  policemen  that 
arrest  intruders  and  enemies  of  the  body,  the  spleen  may 
be  compared  to  police  headquarters.  If  the  white  cor- 
puscles are  compared  to  scavengers,  then  the  spleen  corre- 
sponds to  the  dumping  and  burning  ground  of  the  health 
department ;  for  impurities  are  destroyed  there,  even  the 
worn-out  red  corpuscles  being  broken  up  and  destroyed  in 
tJie  spleen.  It  is  not  surprising  that  when  the  body  is 
filled  with  malarial  or  other  poison,  the  spleen  sometimes 
becomes  of  an  enormous  size.  White  corpuscles  are  prob- 
ably formed  in  the  spleen ;  the  old  white  corpuscles  are 
destroyed  chiefly  in  the  smaller  lymph  glands. 


HYGIENE  OF  THE  CIRCULATION 

The  importance  to  health  of  a  good  circulation  may  be 
judged  from  accidents  that  have  happened  to  a  limb.  All 
of  the  nerves  that  supplied  the  limb  of  an  animal  have 
been  cut.  The  limb  was  paralyzed,  but  the  circulation 
was  active,  the  hair  and  nails  continued  to  grow,  the  limb 
remained  warm,  and  the  only  change  besides  paralysis  was 


98  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

some  loss  in  size.  In  the  case  of  another  limb,  however, 
in  which  the  arteries  had  been  cut  and  the  nerves  left  un- 
injured, it  was  found  that  the  limb  soon  became  cold  ;  in  a 
few  hours  it  was  black,  and  in  a  short  time  the  flesh  began 
to  fall  away.  The  limb  had  died.  The  Bible  says  the 
blood  is  the  life. 

How  the  Muscles  help  the  Circulation.  —  The  imperative 
need  of  muscular  exercise  to  keep  the  body  sound  exists 
because  of  the  lack  of  other  means  to  cause  movement  in 
the  veins  and  lymphatics.  The  pressure  from  the  heart 
extends  through  the  arteries  and  capillaries,  but  soon  dis- 
appears in  the  veins,  and  of  course  the  heart  beat  does  not 
affect  the  lymphatics  at  all.  (Repeat  the  explanation 
already  given,  of  how  a  contracting  muscle,  with  the  aid  of 
the  valves,  causes  the  blood  in  the  veins  to  flow  only  one 
way  ;  it  has  a  similar  effect  on  the  lymph.)  Good  food,  pure 
air,  and  plenty  of  exercise  are  necessary  for  healthy  blood. 
Many  so-called  "  blood  purifiers  "  are  advertised  to  entrap 
the  ignorant.  It  is  impossible  to  imagine  how  "  blood 
purifiers"  can  aid  the  blood.  The  blood  is  purified  not  by 
putting  anything  into  the  blood,  but  by  getting  something 
out.  The  way  to  get  the  waste  material  out  of  the  blood 
is  by  exercise  vigorous  enough  to  cause  deep  breathing, 
active  perspiration,  and  a  free,  rapid  circulation  ;  the 
lungs,  the  skin,  and  the  kidneys  all  send  out  impurities 
brought  to  them  by  the  blood. 

The  one  great  hygienic  effect  of  muscular  exercise  is  an 
active  circulation^  and  from  an  active  circulation  nine  chief 
effects  may  be  traced.  The  effects  upon  the  body  will  be 
given  in  order,  beginning  with  the  surface  —  skin,  fat, 
muscles,  bones ;  and  the  effects  upon  the  internal  organs 
are  given  in  order  of  position,  beginning  with  the  highest 
—  brain,  lungs,  heart,  digestive  organs. 


THE   CIRCULATION  99 

The  Nine  Effects  of  an  Improved  Circulation.  —  i.  The 
skin  is  made  fresh,  pink,  and  smooth  from  the  flushing  of 
the  capillaries ;  it  is  purified  by  the  perspiration  and  the 
renewal  of  cells. 

2.  If  the  fat  is  too  great  in  amount,  it  is  burned  up ;  if 
it  is  too  small  in  amount,  the  better  nourishment  brought 
by  the  blood  increases  it. 

3.  The  muscles  are  better  fed  (colored   Fig.   12)  and 
grow  firm,  strong,  and  large. 

4.  The   skeleton    is   held    in    proper    position    by  the 
stronger  muscles,  and  deformity  is  prevented. 

5.  The  Brain.      The   pure,  fresh   blood,   loaded   with 
oxygen   from  expanded   lungs,   flushes  every  capillary  of 
the    brain,  clears   the   mind,  and   doubles   or  trebles   its 
power  to  work. 

6.  The  lungs  are  expanded  if  the  exercise  be  rapid  and 
vigorous. 

7.  The  Heart.      Every   contracting    muscle    aids    the 
heart  in  its  work. 

8.  The  Stomach.      Exercise  burns   up  the   food    and 
increases  the  appetite. 

9.  General    Effects.       Exercise    moves    the    stagnant 
lymph  and  renews  the  lymph  in  every  tissue  ;  it  promotes 
good  humor,  decreases  loafing,  cigarette  smoking,  gossip- 
ing, and  other  vices. 

When  the  red  corpuscles  of  blood  are  too  few  the  person 
is  said  to  have  ane'mia.  Children  with  a  tendency  toward 
thin  blood,  or  anemia,  are  likely  to  be  pale,  to  catch  cold 
readily,  and  to  have  flabby  muscles  and  a  poor  appetite. 
This  may  be  the  result  of  naturally  delicate  health,  or  of 
improper  bringing  up.  In  either  case  it  is  absolutely  nec- 
essary that  the  child  have  plenty  of  fresh  air,  sunshine, 
and  sleep,  with  gradually  increasing  muscular  exercise. 


IOO  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

The  custom  that  prevails  in  some  schools  of  giving  work 
that  requires  children  to  study  at  night,  is  a  very  bad  one. 
A  poorly  ventilated  schoolroom  or  sleeping  room  is  dan- 
gerous to  the  health  of  children.  Anemia  may  also  appear 
with  developing  girls  and  fast-growing  boys  just  entering 
the  high  school.  Harmonious  development  of  both  mind 
and  body  is  needed,  not  merely  the  cramming  of  the  mind 
with  books.  Unfortunately,  parents  often,  from  lack  of 
judgment  or  from  vanity,  spur  their  weak  children  on  to 
exclusively  mental  effort,  that  they  may  take  first  places  at 
school.  The  teacher  or  the  physician  should  persuade 
parents  to  take  such  a  pupil  away  from  school  for  a  year 
or  more,  that  the  brain  may  have  rest.  Cold  baths,  trips 
to  the  country,  suitable  diet,  outdoor  games,  the  preserva- 
tion of  childlike  feeling,  and  the  avoidance  of  exciting 
novels  and  fashionable  follies  are  more  needed  than  edu- 
cation or  drugs  in  such  cases.  Sometimes  factory  women 
are  anemic  because  they  do  not  eat  enough  of  foods  rich 
in  nitrogen.  They  wrongly  think  that  such  food  as  eggs, 
cheese,  and  meat  are  too  expensive.  Factory  girls  and 
shop  girls  whose  work  requires  them  to  stand  all  day,  and 
who  live  at  a  long  distance  from  their  work,  should  not 
walk  home  at  night  to  save  car  fare. 

The  Effect  of  tobacco  upon  the  heart,  especially  if  ciga- 
rettes are  used,  is  sometimes  to  cause  attacks  of  irregular 
beating;  the  heart  flutters  faintly  for  a  while,  then  palpi- 
tates strongly,  then  flutters  again.  This  trouble  is  called 
tobacco  heart,  or  trotting  heart. 

Effect  of  Alcohol  upon  the  Circulation.  —  After  a  person 
has  taken  an  alcoholic  drink  his  face  and  skin  are  likely  to 
become  flushed,  and  perhaps  his  heart  beats  faster.  Most 
investigators  have  found  that  the  alcohol  itself  does  not 
directly  increase  or  strengthen  the  action  of  the  heart. 


THE   CIRCULATION1  IOI 

Hence  it  is  wrong  to  call  alcohol  a  heart  stimulant.  The 
'ively  muscular  movements  a  man  may  make  when  his 
judgment  is  slightly  clouded  by  alcohol  and  the  general 
lerangement  of  the  body  by  the  alcohol  may  cause  his 
heart  to  beat  faster.  The  flushing  of  the  skin  is  believed 
to  be  due  to  the  relaxing  effect  which  alcohol  has  upon 
the  little  muscle  fibers  in  the  walls  of  the  blood  vessels. 
The  narcotic  effect  of  alcohol  is  much  more  powerful  than 
its  irritating  or  stimulating  effect.  The  effect  of  alcohol 
in  causing  fatty  degeneration  of  the  muscles  often  weakens 
the  heart  and  other  blood  vessels. 

PRACTICAL  QUESTIONS. — 1.  Through  what  kind  of  skin  do  the 
blue  veins  in  the  wrist  show  most  plainly  ?  Because  people  who  do 
no  physical  labor  often  have  such  skins,  they  are  sometimes  termed 
"  blue-blooded  aristocrats.1'  Would  you  prefer  to  belong  to  the  "  blue- 
blooded  aristocracy"  or  to  the  red-blooded  aristocracy  ?  2.  Which  is 
more  compressible,  a  vein  or  an  artery  ?  Does  a  tight  garter  interfere 
more  with  the  flow  of  blood  to  the  feet  or  from  the  feet  ?  3.  Why 
are  those  who  take  little  exercise  likely  to  have  cold  feet?  (p.  98.) 

4.  What  is  the  purpose  of  a  linen  cuff?    What  is  the  purpose  of  a 
linen  collar  ?    Why  is  it  unnecessary  to  have  a  collar  as  high  in  front  as 
behind  ?     What  two  evil  effects  to  the  neck  result  from  such  a  collar? 

5.  Where  does  the  so-called  venous  blood  flow  through  an  artery  ? 
(p.   91.)      6.   What  vein   begins   and   ends   in  capillaries?      (The 
portal  vein,  p.  91.)       7.    To  what  purifying  organ,  after  leaving  the 
lungs,  does  the  heart  send  part  of  the  blood  before  the  blood  has  had  a 
chance  to  become  impure  ?    (Colored  Fig.  2.)    8.  What  keeps  the  blood 
moving  between  the  beats  of  the  heart  ?     (p.  82.)      9.  Why  does  rub- 
bing wear  out  a  shoe,  although  it  causes  a  corn  to  grow  on  the  skin  ? 
Is  the  pressure  of  a  tight  shoe  constant,  or  does  it  change  at  every  step  ? 
How  would  this  affect  circulation  and  nutrition  in  the  tot  ?      10.  Rid- 
ing in  a  jolting  vehicle  assists  especially  what  part  of  the  circulation  ? 
(p.  96.)     11.  Why  is  it  best  that  the  blood  flows  slowly  through  the 
capillaries  ?      12.  What  cells  need  no  lymph  spaces  in  order  to  get 
their  nourishment  ?     (Fig.  84.)       13.  How  may  internal   organs   be 
relieved  of  congestion?     How  may  the  skin  be  caused  to  glow  with 
blood  ?    14.  Why  does  a  boy  who  smokes  have  less  prospect  for  sue- 
cess  in  life  than  he  would  have  if  he  did  not  smoke  ? 


UNIVERSITY 

OF 


Colored 

Circulation  ant)  Urspinuion 


PLATE  X 


FJG.  2.  —  KIDNEYS 
AND  BLADDER. 


FIG.  3.  —  CELLS  AND  CAPILLA- 
RIES OF  LIVER  (magnified). 


FIG.  i.  —  DIAGRAM  OF  CIRCULATION. 


FIG.  4.  — HEALTHY  Mucous 
MEMBRANE. 


.-..,<•   ;      -   '  «.       ; 

FIG.  5.  —  Mucous  MEMBRANE  in- 
flamed by  catarrh  or  alcohol. 


PLATE  XI 


rft/sc/e  ce//s 


FIG.  6.  — THE  LYMPH  SPACES. 


FIG.  7.  — DIAGRAM  OF  AIR  CELL. 


Hyoid  bone 


Thyroid 
cartilage 

CricoM 

cartilage 
Trachea 

OCsophagus 


— Aortic  arch 


— Left  bronchus 
Thoracic  aorta 
(Esophagus 


FIG.  9.  —  RELATION  OF  SPINE, 
TRACHEA,  AORTA,  GULLET, 
AND  STOMACH. 


FIG.  8.— DIAGRAM  OF  CAPILLARIES. 


PLATE  XII 


FIG.  ii.  — GASTRIC  GLAND, 
WITH  CAPILLARIES. 


FIG.  io.  — DIAGRAM 
OF  HEART. 


FIG.  12. — THREE 
MUSCLE  FIBERS. 


FIG.  13.  — LYMPH 
GLAND. 


FIG.  14.  — Six  PAPILLAE,  with  capillaries  and  touch  bodies. 


PLATE  XIII 


9 


FIG.  15.  — THE  THORACIC  DUCT 


FIG.  16.  — RIGHT  AND  LEFT  VAGUS 
NERVES  to  lungs,  aorta,  heart  (re- 
moved), stomach,  and  liver.  (Dia- 
gram.) 


JFtgure*  m  Cftatt 

1.  Diagram  of  Circulation 

2.  Mionegs  ano  Elaofcer 

3.  Cells  ano  Capillaries 

4.  I^ealtfjg  fflurous  fHembrane 

5.  Catarrljal  fHurous  fftnnbrane 

6.  Itgmpl)  Spares 

7.  Diagram  of  3Ur  Cell 

8.  Diagram  of  Capillaries 

9.  delation  of  Spine,  fEradjea,  'Sorta, 

©ullet,  ano  Stomarfj 


10.  Diagram  of 

11.  (Sastric  @lano  toitl)  Capillaries 

12.  fftirroscopic  l"icto  of  fflusrle  JFibers 

13.  Egmpfj  (Slanos 

l  '».  papillae,  magnifieU 

15.  STfjoradc  Duet 

16.  Fagus  Neroes  to  3$cart  ano  Eungs 


CHAPTER   VI 

• 

THE  RESPIRATION 

The  Nature  of  a  Breathing  Organ. — The  blood  sent  to 
the  tissues  soon  becomes  dark  because  of  loss  of  oxygen 
and  absorption  of  impurities.  It  is  then  carried  through 
the  heart  to  the  organ  which  has  the  function  of  supply- 
ing oxygen  and  giving  off  carbon  dioxid.  In  some  small 
animals,  as  the  ameba  and  the  earthworm,  the  surface  of 
the  body  suffices  for  breathing.  But  large  animals  with 
many  deep-seated  and  hidden  cells  require  a  breathing  sur- 
face greater  than  the  area  of  the  skin,  covered  by  cells  of 
specialized  activity.  This  is  supplied  by  having  the  oxygen- 
absorbing  surface  inside  of  the  body,  and  by  having  it  pro- 
vided with  folds  and  tubes  and  minute  cavities  of  great 
complexity.  It  is  estimated  that  if  the  lungs  of  a  man 
were  unfolded  and  all  their  tubes  and  cavities  spread  upon 
one  surface,  an  area  of  more  than  one  hundred  square  feet 
(or  ten  feet  square)  would  be  covered.  This  immense  sur- 
face is  exposed  to  the  air  at  every  full  breath.  Many 
muscles  and  bones,  without  which  the  lungs  would  be 
helpless,  have  a  part  in  breathing. 

Each  respiration,  or  breath,  consists  of  the  passing  in 
of  the  air,  or  inspiration,  sending  it  out,  or  expiration, 
and  a  pause  after  one  but  not  both  of  the  other  stages. 

The  Air  Passages. — The  air  usually  passes  in  at  the 
nose  and  returns  by  the  same  way,  except  during  talking 
or  singing.  If  you  look  in  your  mouth  with  a  mirror 
(Fig.  91),  you  will  see,  at  the  back  part,  an  arch  which  is 

102 


THE  RESPIRATION 


103 


the  rear  boundary  line  of  the  mouth.  Just  above  the  arch 
is  likewise  the  rear  boundary  line  of  the  nasal  passages. 
The  funnel-shaped  cavity  beyond,  into  which  both  the 
mouth  and  nasal  passages  open,  is  called  the  pharynx 
(far' inks),  or  throat  (see  Fig.  91,  also  Fig.  108).  Below, 
two  tubes  open  from  the  pharynx.  One  is  the  trachea 
(tra'kea),  or  windpipe,  the  other  is  the  esophagus,  or  gullet. 
At  the  top  of  the 
trachea  is  the  carti- 
laginous larynx,  or 
voice  box.  If  the 
finger  is  placed  upon 
the  larynx,  or  Adam's 
apple,  it  is  plainly 
felt  to  move  up  and 
down  during  the  act 
01  swallowing.  The 
opening  into  the 
larynx  is  provided 
with  a  lid,  the  epi- 
glottis also  consisting 
of  cartilage.  The 
larynx  will  be  de- 
scribed more  fully  in 
treating  of  the  voice. 
Just  below  it  comas 


.Tongue 


FIG.  91.  — OPEN  MOUTH,  showing  palate  and 
tonsils. 


the 


trachea  proper,  which  is  a 
tube  about  three  fourths  of  an  inch  in  diameter  and 
about  four  inches  long  (Fig.  92).  It  consists  of  hoops 
of  cartilage  (Fig.  92)  which  are  not  complete  circles,  but 
are  shaped  somewhat  like  the  letter  C,  being  completed 
at  the  rear  by  involuntary  muscular  tissue,  whose  func- 
tion is  to  draw  the  ends  together  at  times  (for  instance, 
during  coughing)  and  reduce  the  size  of  the  tube.  The 


IO4 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


function  of  the  hoops  of  cartilage  is  to  keep  the  windpipe 
open  at  all  times.  If  it  should  be 
closed  by  pressure,  life  might  be  lost. 
You  may  feel  these  rings  of  cartilage 
in  the  neck. 

The  lower  end  of  the  trachea  is 
just  behind  the  upper  end  of  the 
breastbone ;  there  it  divides  into  two 
large  tubes.  These  subdivide  into  a 
great  number  of  smaller  branches, 
called  bronchial  tubes.  Cartilage  is 
found  in  the  walls  of  all  but  the 
smallest  of  the  tubes.  The  sub- 
division continues,  somewhat  like  the 
branching  of  a  tree,  until  the  whole 
lung  is  penetrated  by  bronchial  tubes. 
Each  tiny  tube 

FIG.  92.  — THE  TRACHEA,  finally  ends  in 
a  wider  funnel- 
shaped  chamber 

called  a  lobule  (Fig.  93),  into 

which   so    many  dilated  sacs, 

called  air  cells,  open,  that  the 

walls  of  the  terminal  chamber, 

or  lobule,  may  be  said  to  con- 
sist of  tiny  cups,  or  air  cells, 

placed  side  by  side.     The  lob- 
ules, or  clusters  of  air  cells, 

are  chiefly  near  the  surface  of 

the  lung.     (The  word  "cell" 

is   here    used    in    its    original  FIG.  93.— A  LOBULE  OF  THE  LUNGS, 

T  . .  showing  air  tubes  and  air  sacs. 

sense   to   denote  a  cavity  or 

chamber,   and   not   in   the   sense  of  a  protoplasmic  cell.) 


h,  hyoid  bone;  e,  epiglottis; 
/,  /',  c,  cartilages  of  larynx. 


THE  RESPIRATION  1 05 

The  air  cells  are  elastic  and  enlarge  by  stretching  as  the 
chest  expands ;  hence,  the  cells  must  have  many  of  the 
yellow  elastic  fibers  of  connective  tissue  in  their  walls. 
They  are  lined  with  thin  epithelial  cells  through  which 
oxygen  and  carbon  dioxid  are  exchanged.  In  the  partitions 
between  the  air  cells  there  is  a  network  of  capillaries.  The 
dark  red  blood  comes  into  these  capillaries  from  the  pulmo- 
nary arteries,  and  is  changed  to  a  bright  red  by  the  time 
it  leaves  them  to  enter  the  pulmonary  veins  (see  colored 

Fig.  7> 

Most  of  the  mucous  membrane  lining  the  air  passages 
has  a  surface  layer  of  ciliated  cells.  Cilia  are  tiny,  hair- 
like  projections  (Fig.  94)  which  continually  wave  to  and 
fro,  the  quicker  stroke  always  being  outward ;  for  their 
function  is  to  remove  particles  of  dust  and  germs  that 
may  find  entrance  to  the  air  passages.  When  the  mucus 
containing  the  dust  is  raised  nearly  to  the  larynx,  it  may  be 
thrown  out  by  coughing.  Near  the  opening  of  the  nostrils 
are  placed  many  ordinary  hairs,  hundreds  of  times  larger 
than  cilia,  through  which  the  air  is 
strained  as  it  enters  the  nose. 

The  Lungs.  -  -  The  entire  chest 
cavity  is  occupied  by  the  lungs  ex- 
cept the  space  occupied  by  the 
heart,  the  larger  blood  vessels,  and 
the  gullet.  The  right  lung  has  three 

lobes,  or  divisions,  and  the  left  lung 

FIG.     94.  —  CILIATED 

has  two  lobes.     The  lungs  are  light          CELLS,  lining  the  air 
pink  in  early  life,  but  become  grayish 
and  darker  as  age  advances.     This  change  is  more  marked 
in  those  who  dwell  in  cities,  or  wherever  the  atmosphere 
is  smoky  and  dusty.     Trie  lungs  are  covered  and  inclosed 
by  a  smooth  membrane  called  the  pleura.    This  membrane 


io6 


LESSONS 


HYGIENIC  PHYSIOLOGY 


turns  back  and  lines  the  chest  wall,  so  that  when  the  chest 
expands,  the  two  sleek  membranes  glide  over  each  other 
with  far  less  friction  than  would  be  the  case  if  the  lungs 
and  chest  wall  were  touching. 

Experiment  17.  The  fresh  lungs  of  a  beef  when  thrown 
upon  water  will  float.  If  the  air  is  forced  into  the  lungs 
through  a  tube  inserted  in  the  wind- 
pipe, they  will  swell.  Just  so  soon 
as  one  ceases  to  blow  into  the  lungs, 
they  begin  to  contract  because  of 
the  elastic  walls  of  the  air  cells. 

The  Respiratory  Muscles.  —  The 
chief  breathing  muscles  are  the  dia- 
phragm (see  Figures  95  and  96), 
the  muscles  forming  the  abdominal 
walls  (see  Figures  64  and  65),  and 
two  sets  of  short  muscles  (an  in- 
ternal and  an  external  set)  between 
the  ribs.  You  may  have  noticed 
these  muscles  when  eating  pork 
ribs.  The  diaphragm,  which  is 
shaped  like  a  bowl  turned  upside 
down,  rounds  up  under  the  base  of 
the  lungs  somewhat  like  a  dome 
and  separates  the  chest  from  the 
abdomen.  Its  hollow  side  is  toward 
the  abdomen  and  its'  edges  are 
attached  to  the  lowest  ribs  and  the 
vertebra  of  the  loins.  Inspiration 

is  brought  about  by  the  rising  of  the  ribs  and  the  descent 
of  the  diaphragm.  Expiration  takes  place  when  the  dia- 
phragm is  raised,  and  the  ribs  descend.  See  Figures  95 
and  96. 


FIG.  95.  —  VERTICAL  SEC- 
TION OF  TRUNK,  show- 
ing diaphragm,  cavities 
of  thorax,  and  abdomen. 


THE  RESPIRATION 


107 


Observation  of  a  Breath.  —  Empty  your  lungs  as  com- 
pletely as  possible,  and  then  place  one  hand  on  each  side 
of  the  body  with  the  thumbs  backward  and  the  finger  tips 
touching  at  the  waist  in  front.  On  taking  a  deep  breath 
you  feel  the  chest  enlarging  at  the  sides  and  in  front.  How 


(Esophagus 


Aorta 


Internal 
ligament 
External 
ligament 


MCSCLB 


FIG.  96.  —  DIAPHRAGM  (or  midriff),  seen  from  below.     (Cunningham.) 

The  centra]  portion  (light)  is  tendinous.  As  the  diaphragm  descends,  it  acts  like  the  piston 
of  a  great  pump  and  the  blood  is  forced  up  through  the  vena  cava,  and  the  lymph  through 
the  thoracic  duct  (colored  Fig.  15). 

far  apart  are  your  finger  tips  now  ?  Expel  the  breath,  and 
the  fingers  come  together  again.  Take  another  breath  with 
the  hands  on  the  abdominal  walls  and  notice  how  they 
move  during  inspiration  and  expiration.  The  number  of 
breaths  is  about  eighteen  per  minute  —  one  fourth  the 
number  of  heart  beats. 


io8 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


Experiment  18.  Study  the  breathing  of  human  beings, 
cows,  and  other  animals,  noticing  the  manner  of  breathing 
and  counting  the  number  of  breaths  per  minute. 

THOUGHT  QUESTIONS. —  Why  breath- 
ing with  the  waist  is  easier  than  breath- 
ing with  the  upper  chest. 

I .  There  are  two  pairs 

of ribs  below,  while 

there    are    none   above. 
2.  There  are  three  pairs 

of ribs  below,  while 

there  are  none  above,  but 
all  the  ribs  of  the  upper 

chest  are ribs. 

3.  The  lower  of 
the  joints  between 
the  seven  pairs  of 
true  ribs  and  the 
sternum  are  more 
flexible  than  the 
upper  joints  be- 
cause  .  (Ob- 
serve the  joints  in 
Fig.  98.)  4.  The 
walls  of  the  waist 

swing    and 

,    while     the 

walls  of  the  upper 
chest  must  move 

and .  5. 

The  bones  of  the 

rest  upon  the  upper 

chest.      In  upper  chest 
breathing   their   weight, 
the    weight   of   both   of 

,  must,  therefore,   be 

lifted.      (Fig.   33.)      Test  by 
FIG.  97.— THE  CHEST,  from  the  right  side,  trying  it. 

Experiment  19.  Let  the  teacher  mark  the  beginning  and 
end  of  a  minute  by  tapping  a  bell.  Count  the  number  of 


THE  RESPIRATION  \ 09 

times  you  breathe  per  minute  while  sitting;  also  the  num- 
ber just  after  the  school  rises  and  takes  vigorous  gymnastic 
movements  for  five  minutes. 


FIG.  98.  — BONES  OF  THE  CHEST,  seen  from  the  front 

Inspiration.  — When  the  diaphragm  contracts,  it  flattens 
and  descends,  and  the  lungs  descend  with  it,  thus  lengthen- 
ing the  chest  from  top  to  bottom ;  at  the  same  time  the 
ribs  are  raised  upward  and  outward  (Fig.  99)  by  the  con- 
traction of  the  outer  set  of  muscles  between  the  ribs. 


no 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


Thus  the  chest  is  made  longer,  broader,  and  deeper  from 
front  to  back.  The  lungs  expand  when  the  chest  expands, 
and  the  air  rushes  in.  Why  is  this  ?  The  lungs  contain 
no  muscles  and  cannot  expand  themselves  ;  the  air  cannot 
be  pulled  in,  for  its  parts  do  not  stick  together.  The 
explanation  is  that  the  air  has  weight.  The  atmosphere 
has  a  height  of  many  miles,  and  the  air  above  is  pressing  on 
that  below.  When  the  chest  walls  are  raised,  there  would 
be  an  empty  space  or  vacuum  between  these  walls  and  the 
lungs  did  not  the  pressure  of  the  outside  air  push  air 
through  the  windpipe  into  the  lungs  and  expand  them. 

Expiration.  —  In  very  active  breathing  the  abdominal  walls 
actively  contract  so  that  they  press  strongly  upon  the  diges- 

tive organs,  which  in  turn  press 
the  diaphragm  up.  The  ribs  are 
also  drawn  down  and  in.  Thus 
the  chest  becomes  smaller  and 
forces  the  air  to  flow  out  through 

1  1  if  \zzQ^\    t^ie  wmdpipe.     D^w  in  the  ab- 

//  /  /  \   ^\     dominal  walls  with  a  jerk  ;  what 

is  the  effect  upon  the  breath  ? 

Why  the  Diaphragm  ascends 
during  Expiration.  —  Pupils  some- 
times get  the  idea  that  when  the 
diaphragm  relaxes  it  springs  up 
into  place.  The  diaphragm  has 
no  more  elasticity  than  a  piece 

of  cloth.      It  relaxes  after  the 
FIG.  99.—  BLACKBOARD  SKETCH,  .  .  .  .  . 

to  show  how  the  chest  is  ex-  breath  is  drawn  in,  and  it  would 


panded  when  the  ribs  move  up-    f   jj  Qf 
ward  and  outward. 


Qwn  weight  if    it  were 

not  supported  by  the  organs  be- 

neath it.     In  reality,  these  organs  have  been  compressed, 
and  the  abdominal  walls  which  contain  them  have  been 


THE  RESPIRATION  III 

slightly  stretched  by  the  descent  of  the  diaphragm,  and 
when  it  relaxes,  it  is  lifted  by  the  expansion  of  thest 
organs,  and  by  the  pressure  from  the  pulling  in  of  the 
elastic  abdominal  walls  (see  Fig.  95). 

Why  Expiration  in  Quiet  Breathing  is  Passive.  —  In  ordi- 
nary quiet  breathing  the  breath  is  actively  inhaled,  but  is 
exhaled  without  muscular  effort.  This  is  because  during 
inspiration  the  air  cells  are  stretched,  and  the  cartilages 
connecting  the  ribs  with  the  sternum  are  slightly  bent. 
The  straightening  of  the  cartilages  causes  the  ribs  to  be 
lowered.  This,  with  the  contraction  of  the  stretched  air 
cells,  forces  the  breath  out  (Figs.  97,  98). 

Experiments.  —  20.  Try  breathing  with  (i)  muscular  in- 
spiration and  passive  expiration  ;  (2)  muscular  expiration 
and  passive  inspiration  ;  (3)  with  both  motions  muscular. 
21.  Finally,  cease  to  notice  your  breathing  for  several 
minutes,  and  then  notice  it  again  without  disturbing  it, 
and  see  which  of  these  three  methods  you  are  using. 

Chest  Breathing,  Abdominal  Breathing,  Full  Breathing. 
—  These  forms  depend  upon  whether  the  breathing  is  car- 
ried on  by  using  the  muscles  of  (i)the  chest,  (2)  the  abdo- 
men, or  (3)  both  (see  Figs.  100,  101,  102).  There  has 
been  much  debate  among  physicians,  surgeons,  and  singers 
as  to  which  of  these  methods  is  best.  Probably  this  ques- 
tion would  not  have  been  raised  but  for  the  confining  and 
deforming  effect  of  clothing  upon  the  waist.  Full  breath- 
ing  is  used  by  children  of  all  races,  by  both  men  and 
women  of  wild  tribes,  and  by  men  and  children  of  civilized 
countries.  It  is  undoubtedly  the  natural  way,  as  well  as 
the  easiest  and  most  effective  way.  Breathing  with  the 
upper  chest  is  exhausting  because  of  the  stiffness  of  the 
upper  part  of  the  bony  cage  (see  Fig.  98) ;  for  it  is  in- 
closed by  true  ribs  fixed  to  the  breastbone  by  short  carti- 


112 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


lages.     The  ribs  in  the  waist  (Fig.  97)  are  either  floating 
in  front  or  fixed  by  long  cartilages  to  the  ribs  above.     In 


FIG.  ioo. 


FIG.  101. 


FIG.  102. 


Fig.  ioo.  —  Female  figure  encased  in  corset.     Expansion  at  the  waist  is  here  impossible  and 

the  breathing  is  called  "  collar-bone  breathing.  " 
Fig.   101.  —  Male  figure.     Here,  owing  to  pressure  of  clothing  and  faulty  position,  expansion 

of  chest  is  hindered  and  breath  is  taken  by  the  "  abdominal  method." 
Fig.  102.  —  Figure  properly  poised  and  free.     Here  the  entire  thorax  can  move  freely,  and 

natural  breathing  is  the  result.     (For  blackboard.) 


pure  abdominal  breathing  the  diaphragm  must  contract 
more  than  in  full  breathing  in  order  to  descend,  because 
its  edges  have  been  drawn  together  and  fixed  by  binding 
the  ribs  at  the  waist.  In  full  breathing  the  floating  and 
false  ribs  at  the  waist  (five  pairs  in  all)  float  in  and  out 
as  nature  provided.  As  they  move  out,  this  broadens  and 
deepens  the  chest,  and  aids  the  flattening  of  the  diaphragm 
by  moving  its  edges  farther  apart. 

Experiment  22.  Place  your  hands  upon  the  sides  of  your 
waist,  and  while  breathing  deeply,  notice  whether  the  ribs 
move  in  and  out.  Many  people  have  lost  this  power  for  life 
by  wearing  belts  or  other  articles  of  clothing  of  such  a  size 
as  not  to  allow  for  expansion.  Their  vital  powers  and 
endurance  are  crippled.  It  usually  proves  to  be  a  per- 
manent loss  (see  Figs,  no,  in). 


THE  RESPIRATION  113 

THOUGHT  QUESTIONS.  —  Write  7,  E,  or  IE  after  each  word  in  this 
list  according  as  inspiration,  expiration,  or  both  are  involved  in  the 
action.      Sighing,       sobbing,       crying    (of  a  child),      coughing, 
laughing,       yawning,       sneezing,       hiccoughing,       snoring. 

Three  Experiments  on  Expired  Air.  —  23.  If  you  breathe 
on  a  cold  window  pane,  you  notice  that  the  glass  soon 
becomes  covered  with  water.  24.  If  you  breathe  through 
a  tube  or  straw,  or  the  hollow  stem  of  a  weed,  into  a  bottle 
of  clear  limewater  (Fig.  103),  the  water  soon  has  a  milky 
appearance ;  only  carbon  dioxid  has 
this  effect.  Limewater  may  be  ob- 
tained from  the  drug  store,  or  it 
may  be  made  by  pouring  water  upon 
a  lump  of  unslaked  lime  and  draining 
it  off  when  the  lime  has  settled. 
25.  If  you  breathe  for  several  min- 
utes upon  the  bulb  of  a  thermometer, 

even  on  a  cold  day,  the  mercury  will 

L .  „        „,.  .  .  FIG.  103.  —  BREATHING 

rise  rapidly.     Thus  three  things  are     THROUGH  LIMEWATER. 

proved ;  water  and  carbon  dioxid  are 

given  off  from  the  lungs,  and  carry  much  heat  from  the 

body  with  them. 

Difference  between  Inspired  and  Expired  Air.  —  The 
air  entering  the  lungs  consists  of  about  one  fifth  oxygen 
and  four  fifths  nitrogen.  This  nitrogen  is  of  no  use  to  the 
body,  and  is  exhaled  unchanged.  About  one  fourth  of  the 
oxygen  inspired  is  taken  up  by  the  blood,  and  carbon 
dioxid  sent  out  in  its  place  (see  colored  Fig.  7).  The 
oxygen  absorbed  by  the  blood  amounts  to  one  and  four 
fifths  pounds  each  day.  The  inspired  air  contains  a  small 
amount  of  watery  vapor;  the  expired  air  contains  much 
more.  About  half  a  pint  of  water  is  given  off  through  the 
lungs  in  a  day.  Minute  quantities  of  injurious  animal 


114  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

matter  are  also  given  off  in  the  breath  from  even  the 
soundest  person,  while  one  with  decayed  teeth,  catarrh, 
indigestion,  lung  troubles,  or  other  unsoundness  gives  off 
still  more  of  this  material.  When  many  people  are  assem- 
bled in  a  badly  ventilated  room,  the  amount  of  injurious 
animal  matter  in  the  air  is  much  increased,  and  it  is  called 
"  crowd  poison"  Its  odor  is  strong  and  repulsive  to  one 
who  just  enters  the  room,  but  the  sense  of  smell  becomes 
dull  to  it  in  a  few.  minutes.  It  would  seem  that  nature 
gives  a  fair  warning  against  harm ;  but  if  we  disregard  the 
warning,  it  soon  ceases. 

Experiment  26.  Fill  a  fruit  jar  with  water  and  take  it 
into  a  room  containing  many  people.  Pour  out  the  water. 
Pour  in  two  tablespoonfuls  of  clear  limewater  and  shake. 
If  the  limewater  turns  milky,  the  ventilation  is  bad. 

People  who  are  really  Unclean.  —  Air  once  breathed  is 
impure.     It  is  just  as  unfit  to  enter  our  bodies  as  muddy 
water    or   decayed   food.      Yet   many   who 
call    themselves    cleanly    and    refined,    and 
will  not  allow  a  speck  of  dirt  to  remain  on 
their  clothes,  nor  use  a  spoon  just  used  by 
another,  do  not  object  to  breathing  into  their 
lungs,  over  and  over  again,  the  cast-off  air 
from  the  lungs  of  others.     If  a  window  is 
opened    for   ventilation,   they    are    horror- 
struck   for  fear  of  drafts.      Drafts  are   in- 
jurious  only   to   persons    perspiring,   or  to 
those   who   have  coddled  the  skin  by  con- 
FIG.   104.  —  inlet  tinually  overheating   it.      There   are  thou- 
ai^p'of  wood.'     sands  of  schools,  churches,  and  theaters  all 
over   the    land  which    reek  daily  with   the 
malodorous  particles  from   the  lungs  of   their  occupants. 
Although  the  air  in  them  is  odorless  to  those  who  occupy 


THE  RESPIRATION 


them,  it  is  disgusting  to  any  one  who  enters  from  the 
fresh  air.  Figure  105  shows  a  ventilated  schoolroom. 

Dust  is  injurious,  and  gradually  weakens  the  lungs  of 
those  who  breathe  it.  Intelligence  and  common  sense  are 
necessary  to 
prevent  it  from 
accumulating 
in  the  house. 
The  chief  pur- 
pose of  house 
cleaning  should 
be  not  only  to  FlG  105.— CORRECT  VENTILATION  OF  SCHOOLROOM. 

remove    DItS  OI        How  are  the  inlet  and  outlet  situated  with  reference  to  the  stove? 

paper  from  the 

floor,  which  do  no  harm  even  to  the  shoes,  but  to  remove 
impurities  from  the  air.  It  does  no  good  to  stir  up  the 
dust  and  allow  it  to  settle  down  again.  In  many  houses 
dust  is  thus  allowed  to  accumulate  for  months.  Experi- 
ments show  that  dust  and  germs  floating  in  the  air  are 
not  diminished  to  a  great  extent  by  a  gentle  draft 
through  the  room.  The  windows  must  be  open  and 
sweeping  done  in  the  direction  of  the  air  currents ;  the 
windows  should  be  left  open  for  a  long  while  after  the 
sweeping}-  A  windy  day  is  best  for  sweeping.  With  all 
precautions  some  dust  may  settle  down.  This  should  not 
simply  be  stirred  up  again  with  a  feather  duster,  but  the 
dusting  should  be  done  with  a  damp  cloth.  Carpet  sweep- 
ers, but  never  brooms,  should  be  used  upon  carpets.  Car- 
pets and  lace  curtains  are  truly  dust  traps,  in  which  dust 

1  The  habit  some  housekeepers  have  of  buying  furnishings  and  bric-a-brac 
for  the  home  until  it  looks  like  a  retail  store  or  junk  shop,  makes  it  almost 
impossible  to  clean  their  houses.  A  few  articles,  carefully  selected,  adorn  a 
home  more  than  many  bought  at  random,  and  they  do  not  litter  the  bouse 
and  serve  as  traps  for  dust. 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


will  accumulate  without  limit.  Those  who  value  the  health 
will  not  use  them,  at  least  in  bedrooms.  Though  linoleum, 
bare  floors,  oiled  and  painted  floors^ 
may  not  look  so  comfortable,  they 
bring  far  more  comfort  in  the  end. 
The  weakening  effect  of  ordinary  dust 
is  one  of  the  chief  causes  of  lung 
diseases,  and  prepares  a  fertile  soil 
for  the  consumptive  germ.  The  spu- 
tum coughed  up  by  consumptives 
falls  upon  the  floor  or  street,  soon 
dries,  and  the  germs  are  driven  about 
by  the  wind.  In  many  cities  there 
is  a  law  against  spitting  in  public 
places,  and  the  streets  are  flushed 
with  water  before  they  are  swept. 

Ventilation  presents  no  difficulties 
in  the  summer  time  or  in  warm  cli- 
mates. The  reason  that  it  is  a  difficult 
question  in  cold  weather  is  because  the  air  furnished  must 
be  not  only  pure,  but  warm.  Heating  with  hot  air,  by 
which  system  pure  air  is 
passed  over  a  furnace  and 
fresh  air  constantly  admitted, 
is  a  good  method  (Figs.  106, 
107).  Heating  by  hot  water 
circulating  in  pipes,  or  by 
steam,  gives  no  means  of 
introducing  fresh  air,  and  is  FlG  I07._ A  passage  behind  afire- 
likely  to  cause  worse  ventila- 
tion than  any  other  method. 

The  radiators  for  both  of  these  systems  should  stand  close 
to  windows  or  other  fresh-air  inlet,  that  the  air  may  be  heated 


FlG.  ro6.  —  The  air  enters 
through  a  special  inlet 
and  is  warmed  as  it 
passes  through  hood 
surrounding  the  stove,- 


"~^ 


place,  or  grate,  in  which  the  air  is 
warmed  as  it  enters. 


THE  RESPIRATION 


117 


as  it  enters ;  and  the  outlet  for  air  should  be  farthest  from 
the  radiators.  The  same  rules  apply  to  heating  by  stoves. 
Heating  by  fireplaces  (Fig.  107)  is  the  most  healthful  of  all 
methods,  for  there  is  a  constant  removal  of  air  through 
the  chimney,  and  this  air  will  be  replaced ;  even  if  all 
doors  and  windows  are  closed,  it  will  come  in  through  tiny 
cracks.  Fireplaces,  however,  do  not  afford  sufficient  heat 
in  severe  climates.  Stoves  are  not  as  healthful  as-  fire- 
places, for  there  is  not  so  much  air  removed  through  the 
pipe  as  through  the  chimney.  Be  prepared  to  draw  Figure 
105  on  the  blackboard,  and  explain  it  to  the  class. 

Experiments.  —  27.  Dangle  a  bit  of  paper  by  means  of 
spider  web  from  the  end  of  a  walking  stick  or  ruler.  Hold 
it  by  the  windows  or  openings  intended  for  the  entry  and 
exit  of  air  and  test  if  the  air  moves  as  desired.  28.  The 
whole  class  may  rise  and  test  cracks  around  every  window 
and  door.  Wherever  the  air 
feels  cold  to  the  hand  the  air 
is  entering. 

Reasons  for  breathing  through 
the  Nose  (Fig.  108).  — (i)  The 
many  blood  vessels  in  the 
mucous  membrane  lining  the 
nasal  passages  and  covering 
the  thin,  platelike  bones  (see 
Fig.  164,  also  Fig.  165)  pro- 
jecting into  the  nasal  passages 

FIG.  108.  —  BLACKBOARD  SKETCH. 
so  heat  the  air  that  it  does  not 

irritate  the  bronchial  tubes.  The  blood  in  the  mucous  mem- 
brane heats  the  air  as  hot-water  pipes  heat  the  air  of  a  room. 
The  air  passes  more  gradually  through  the  small  nose  than 
through  the  large  mouth.  (2)  The  hairs  in  the  nostrils 
strain  the  air  and  catch  dust ;  the  cilia  of  the  nasal  pas 


Il8  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

sages  also  do  this.     (3)  A  mouth  breather  often  swallows 
food  before  chewing  it  sufficiently,  because  he  cannot  hold 
his  breath  longer.      (4)  The  nasal  mucous  membrane  of 
an  habitual  mouth-breather  dries  and  shrinks  and  obstructs 
the  circulation,  bringing  on  catarrh  of  the  nose.    (5)  Mouth 
breathing  causes  an  unpleasant  expression  of  countenance 
(see  Fig.    109).      (6)  The   breath 
does  not  come  through  the  nose  as 
quickly   as    through   the    mouth ; 
the  lungs  are  kept  more  expanded, 
and    one    does    not   get    "out   of 
breath  "  so  quickly.     (7)  The  voice 
of  tJie  mouth  breather  has  a  hard 
FIG.  109.— Facial  expression     twang,    not    a    full,  resonant  tone 
LUi^h^ughiSnot    as    when    the   nostrils    are   open. 
(8)    Flavors  and  odors  are  better 

appreciated.  Sometimes  the  sense  of  smell  is  almost  lost 
by  mouth  breathers.  A  frequent  cause  of  mouth  breathing 
is  adenoids,  a  gland-like  growth  in  the  pharynx,  common 
with  children.  These  are  easily  removed  by  a  physician. 
Diseases  of  the  Respiratory  Organs.  —  A  cold,  or  catarrh, 
is  an  inflammation  of  a  mucous  membrane.  If  the  inflamma- 
tion is  in  the  nasal  passages,  it  is  called  a  cold  in  the  head  ; 
.  if  it  is  in  the  pharynx,  it  is  called  a  sore  throat ;  if  it  is  in 
the  larynx,  or  voice  box,  there  is  hoarseness ;  if  it  is  in  the 
bronchial  tubes,  it  is  bronchitis ;  finally,  if  it  is  in  the  air 
cells,  it  is  pneumonia.  If  the  air  is  cut  off  from  access  to 
the  air  cells,  there  is  an  attack  of  the  painful  disease  called 
asthma,  which  is  accompanied  by  a  feeling  of  suffocation. 
Some  believe  that  asthma  is  caused  by  the  mucous  mem- 
brane lining  the  finest  bronchial  tubes  becoming  inflamed 
and  swollen,  and  closing  the  tubes ;  others  think  that  the 
muscles  in  the  large  bronchial  tubes  contract  and  close  the 


THE  RESPIRATION  1 19 

tubes.  Pleurisy  is  inflammation  of  the  pleura.  If  much 
fluid  forms  between  the  pleuras,  the  inner  pleura  may 
press  upon  the  lungs  and  interfere  with  breathing. 

Alcohol  not  only  weakens  the  blood  vessels  near  the  sur- 
face but  the  blood  vessels  in  general.  Weakened  and  con- 
gested blood  vessels  in  the  lungs  make  them  more  liable  to 
pneumonia  and  other  congestive  diseases.  Continual  con- 
gestion causes  an  abnormal  growth  of  connective  tissue 
fiber  in  the  walls  of  the  cells.  This  interferes  with  the 
exchange,  of  carbon  dioxid  and  oxygen. 

Tobacco.  —  It  is  often  asked  why  cigarettes  are  so  much 
more  injurious  to  the  health  than  pipes  and  cigars. '  The 
nature  of  the  paper  of  cigarettes  and  various  other  absurd 
reasons  have  been  assigned.  The  true  reason  is  that 
the  cigarette  smoker  usually  inhales  the  tobacco  smoke. 
Cigar  smoke  drawn  into  the  lungs  would  usually  be 
coughed  up,  but  cigarette  smoke  is  weaker  —  it  is  so  weak 
that  the  smoker  is  not  content  simply  to  absorb  the 
nicotine  through  the  mucous  membrane  of  the  mouth.  He 
draws  it  into  the  lungs.  As  the  surface  of  the  lungs  is  a 
hundred  times  greater  than  the  surface  of  the  mouth,  and 
its  lining  much  thinner,  cigarette  smoking  is  far  more 
injurious  than  cigar  smoking. 

Prevention  of  Colds  and  Other  Respiratory  Diseases.  —  A 
weak  or  deranged  circulation  allows  congestion  or  swelling 
of  the  blood  vessels  to  occur  in  some  weak  part  of  the 
mucous  membrane.  The  capillary  walls  become  injured 
by  the  pressure,  and  blood  escapes  and  stagnates  in  the 
tissues,  causing  inflammation.  The  best  way  to  prevent 
congestion  is  to  strengthen  the  circulation  and  the  nerves 
tJiat  control  it,  so  that  tJie  circulation  will  not  be  deranged 
by  every  slight  strain  or  exposure.  Coddling,  or  overheat- 
ing the  body  and  protecting  it  too  carefully,  often  leads  to 


I2O 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


colds  and  bronchitis.     Clothing  may  flatten  the  chest  and 
deform  the  waist  (Figs,  no,  in,  112).     Bracing  the  skin 

is  the  best  protection 
against  taking  cold. 
Because  of  dress,  and 
by  constantly  living 
in  houses,  the  average 
civilized  man  seems 
to  have  lost  the  power 
which  the  skin  in  sav- 
age races  possesses  of 
reacting  promptly  to 
changes  of  tempera- 
ture. 

Moritz  says  that  it 
is  astonishing  to  see 
how  many  people  cod- 
dle and  weaken  their 

bodies    in    the    most 
FIG.  no.  FIG.  HI. 

FIG.  no.  — Flattened  chest  and  sunken  abdomen  terrible  Way,  simply 
from  wearing  tight  clothing  since  the  age  of  because  the  sensation 
fourteen. 

of   warmth    is   pleas- 

FlG.    in.  —  A    natural  woman.      Women  with 

forms  like  Figure  no  often  walk  with  bodies    anter    to   a  weak  per- 
bent  forward  to  hide  the  prominent  abdomen.       o^  «-V,on  f  Uof  of 


Wearing  clothing  that  is  too  heavy,  sleeping  on  feather 
beds,  or  living  in  a  house  heated  to  a  higher  temperature 
than  seventy  degrees  are  ways  of  weakening  the  body. 
Cold  baths,  clothing  just  warm  enough  to  be  comfortable, 
living  much  in  the  open  air,  harden  and  strengthen  the 
body.  Pneumonia,  consumption,  and  other  serious  lung 
diseases  usually  begin  with  a  cold,  cough,  or  bronchitis. 
This  furnishes  a  weighty  reason  for  so  training  the  body 
as  to  overcome  a  tendency  to  the  lesser  troubles.  People 


THE  RESPIRATION 


111 


who  take  reasonable  care  of  themselves  do  not  have  colds 
so  often  as  once  a  year. 

The  cold  begins  in  the  weakest  spot,  and  with  some  people 
this  is  always  the  same  part ;  for  instance,  the  head.  Many 
people  suffer  constantly  from  cold  feet, 
which  are  either  moist  or  dry ;  this  may 
bring  on  chronic  bronchitis  that  cannot 
be  cured  until  the  circulation  in  the 
feet  is  strengthened  and  warmth  is 

restored.     This  may  be 

done    by  bathing   them 

in  cold  water,  changing 

the  hose  once  or  twice 

a  day,  or  rubbing  them 

J  '  FIG.    112.  —  Suspen- 

ders should  have  a 
pulley  or  lever  at 
the  back,  that  the 
strap  on  one  side 
may  loosen  when 
one  shoulder  is 
raised. 

with  spirits.  Large 
numbers  of  people 
are  so  negligent 
and  careless  about 
their  bodies,  that 
cold  feet,  or  other 
evidence  of  weak 
circulation,  if  not 
accompanied  by  pain,  do  not  attract  their  attention. 
Singing  is  a  good  preventive  of  lung  diseases.  When  the 
lungs  are  congested  and  diseased,  the  patient  may  with 
advantage  take  deep-breathing  exercises  several  times  a 
day.  The  deep  breathing  that  accompanies  vigorous  work 
and  play  is  far  more  beneficial  than  breathing  exercises. 


FIG.  113.  — SPIROMETER  for  testing  the  breathing. 
Average  man  blows  230  cu.  in. ;  woman,  170  cu.  in. 

Average  lung  contains  330  cu.  in.  of  air;  100  cu.  in.  (re- 
sidual air)  cannot  be  sent  out;  beginning  with  the  lungs 
at  rest,  100  cu.  in.  (reserve  air}  may  be  expelled;  30 
cu.  in.  (tidal  bir)  flows  in  and  out  in  quiet  breathing;  at 
the  end  of  a  quiet  inspiration,  100  cu.  in.  (comple mental 
air)  may  still  be  inhaled. 


122  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

PRACTICAL  QUESTIONS.  —  1.  State  how  in  the  case  of  a  person 
of  ungraceful  figure,  a  gradual  remolding  of  cartilages  (which  ones?), 
the  strengthening  of  the  muscles  (which  ones?),  and  the  practice  of 
deep  breathing  may  each  contribute  toward  acquiring  a  correct  and  per- 
fect figure.  2.  Should  a  hat  be  well  ventilated?  (A  punch  for  making 
the  holes  costs  a  dime.)  Should  a  hat  be  stiff  or  soft?  3.  Name 
habits  that  impair  the  power  of  the  lungs.  4.  How  could  you  con- 
vince a  person  that  a  bedroom  should  be  open  while  and  after  it  is 
swept  ?  That  it  should  be  ventilated  at  night  ?  5.  Which  is  the  more  in- 
jurious to  others,  tobacco  chewing  which  causes  the  ground  to  be  unclean, 
or  smoking  which  renders  the  air  impure  ?  6.  Why  do  those  who  stand 
straight  up  to  hoe  not  get  tired  half  so  quickly  as  those  who  bend  or 
"hump"  over?  (Chap. VI.)  7.  Why  do  students  who  sit  in  rocking 
chairs,  or  from  other  causes,  lean  the  head  forward  when  they  study, 
often  find  that  they  recover  from  drowsiness  if  they  sit  erect,  or  sit  in  a 
straight  chair?  8.  How  are  high  collars  a  fruitful  source  of  bad  colds? 
9.  If  the  draft  up  the  chimney  of  the  fireplace,  when  the  fire  is  burn- 
ing, takes  up  a  volume  of  air  sufficient  for  many  people,  why  is  it  unnec- 
essary to  open  a  window?  10.  Why  does  cold,  impure  air  make  a 
person  colder  than  cold,  pure  air?  (p.  14.) 

BACTERIA:   INFECTIOUS  DISEASES 

Independent  Plants  and  Dependent  Plants :  Green  and 
Colorless  Plants.  — Most  plants  get  their  food  directly  from 
the  mineral  kingdom — from  the  solid  minerals  in  the 
earth  and  from  the  gaseous  minerals  in  the  air.  The 
plants  that  do  this  always  live  in  the  light  and  contain 
green  substance.  This  green  substance  is  most  abundant 
in  their  leaves.  By  the  aid  of  the  sunlight,  the  plant  takes 
carbon  dioxid  from  the  air  and  gives  back  oxygen  to 
the  air  (see  Fig.  118).  There  are  some  plants  which 
cannot  use  mineral  foods,  but  must  live  on  dead  plants 
and  use  the  material  which  those  plants  assimilate  from 
minerals.  Such  plants  are  never  green.  Examples  of 
them  are  mushrooms,  toadstools,  devil's  snuffbox,  fungus, 
and  tiny  plants  called  mold,  which  forms  on  bread,  leather, 
etc.,  in  damp  weather. 


THE  RESPIRATION  1 23 

Germs,  or  Microbes.  —  Scientists  were  in  doubt  for  a 
while  as  to  whether  the  microscopic  one-celled  germ  called 
microbes,  or  bacteria,  were  plants  like  mold,  or  animals 
like  the  ameba.  It  is  now  definitely  known  that  germs,  or 
bacteria,  are  vegetables.  They  are  not  green,  hence  they 
must  depend  upon  plants  or  animals  for  food.  There  is 
another  class  of  one-celled  plants,  somewhat  larger  than 
bacteria,  which  are  called  yeast  plants.  Study  the  table 
on  page  124  and  find  how  bacteria,  yeast,  and  mold  differ 
in  size,  food,  reproduction,  products  yielded,  and  condi- 
tions which  favor  their  growth. 

The  Work  of  Bacteria. —  Dead  plants  and  animals  contain 
materials  which  are  of  the  greatest  value  as  food  for  living 
plants  and  animals.  As  other  plants  and  animals  die,  this 
material,  unless  it  decayed,  would  accumulate  until  all  the 
plant  food  would  be  stored  up,  and  all  the  space  needed  by 
young  plants  and  animals  would  be  occupied  by  logs  and 
leaves  and  carcasses,  and  the  earth  would  be  no  longer 
habitable.  There  is  no  decay  without  the  action  of  bac- 
teria, yeast,  or  mold.  Their  work  is  to  destroy  unsound  or 
dead  animal  and  vegetable  matter  by  living  upon  it  as  food. 
Thus  it  is  returned  to  the  soil  arid  air,  ready  to  be  used  as 
plant  food  again. 

Nature  of  Germ  Diseases.  —  A  plant,  as  an  oak  or  a  pear 
tree,  may  become  affected  by  a  disease  called  the  blight, 
and  such  disease  is  usually  regarded  as  a  necessary  evil,  or 
imperfection  in  creation.  Looked  at  with  a  broader  knowl- 
edge, such  disease  is  a  sign  of  growth  as  well  as  of  decay, 
and  is  a  blessing  and  not  a  curse.  The  microscope  shows 
that  trees  affected  with  the  blight  are  the  seat  of  the 
growth  of  millions  of  these  one-celled  plants  called  bac- 
teria. So  where  there  is  death  and  disease,  there  life  is 
also  flourishing.  The  blight  did  not  attack  the  hardy, 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


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THE  RESPIRATION 


125 


sound  pear  trees,  but  those  of  rapid,  sappy  growth,  whose 
tissues  had  already  become  unsound  or  dead,  from  the  effect 
of  frost  or  overcultivation. 

Bacteria  in  the  Human  Body.  —  Bacteria,  or  germs,  do 
not  always  wait  for  the  dead  or  dying  material  to  be 
excreted,  or  separated  from  the  animal  or  plant,  before 
attacking  and  destroying  it.  If  more  food  is  eaten  than 
can  be  digested,  and  it  remains  longer  than  five  hours  in 
the  stomach,  starchy  food  may  ferment  from  the  growth 
of  yeast  plants,  giving 
rise  to  carbon  dioxid 
gas ;  albuminous  food 
may  be  decomposed  by 
bacteria ;  or  a  growth 
of  mold  may  form  on  the 
lining  of  the  organs, 
extending  up  to  the 
mouth  and  forming  a 
coat  upon  the  tongue. 
If  the  lungs  are  never 
fully  expanded,  but  by 
stooping  over  at  work 
or  by  tight  clothing  a 
part  of  a  lung  is  compressed  and  the  blood  supply  inter- 
fered with,  or  if  foul  air  is  constantly  breathed,  cells  and 
tissue  in  the  lungs  may  become  unsound  and  the  bacteria 
may  use  them  for  food.  The  bacillus  tuberculosis  is 
a  form  of  bacteria  that  sometimes  finds  a  fertile  soil  in 
the  lungs.  In  thousands  of  cases  of  consumption,  bacilli 
destroy  an  injured  part  of  a  lung  and  it  heals  over.  This 
is  very  likely  to  happen  if  the  person  returns  to  natural 
ways,  lives  out  of  doors,  and  allows  the  cells  to  purify 
the  body.  Dissections  made  in  medical  schools  show 


FIG.  114.  —  ROD-SHAPED  BACTERIA  (BA- 
CILLI) OF  LOCKJAW.  Some  of  the  bac- 
teria have  an  oval  spore  near  one  end. 
(Peabody.) 


126  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

scars  on  the  lungs  in  thousands  of  cases.  These  scars 
were  left  by  consumption,  with  which  the  persons  had 
been  affected  without  knowing  it  and  from  which  they 
had  entirely  recovered,  dying  afterward  from  another 
disease. 

Bacteria  destroy  the  Weak  and  leave  Room  for  the  Sound 
and  Strong.  —  But  in  many  cases  the  individuals  have 
lived  wrong  physically  for  so  long,  and  their  lungs  have 
become  so  weak,  that  they  are  gradually  destroyed  by  the 
bacilli.  This  is  sad  to  the  individual  and  his  friends  and 
loved  ones,  but  it  is  best  for  the  race,  for  it  prevents 
gradual  degeneration  of  the  race  into  weaklings. 

Whether  the  body  has  been  injured  through  ignorance 
or  self-sacrifice,  through  dissipation  or  selfish  ambition  for 
money  or  fame,  through  foolish  attempts  at  beauty  or 
through  devotion  to  learning,  or  through  unselfish  love  and 
work  for  others,  the  result  is  the  same ;  nature  knows  no 
difference.  However  noble  the  character  or  wise  the  mind 
on  other  subjects  than  health,  when  the  body  has  been 
neglected  or  foolishly  treated,  and  a  vital  organ  has  sunk 
in  health  below  the  standard  necessary  for  a  human  being, 
condemnation  comes. 

Effects  of  Bacteria.  —  They  produce  decay  in  unsound 
tissue.  They  destroy  the  albumin  in  which  they  grow, 
producing  foul-smelling  gases  and  a  number  of  poisons 
called  toxins  if  formed  in  the  living  body,  and  called 
ptomaines  (to' manes)  if  formed  after  death.  Ptomaines  in 
spoiled  meat  cause  most  of  the  symptoms  produced  by 
eating  it.  A  special  kind  of  ptomaine  sometimes  forms  in 
milk  and  ice  cream  that  has  been  kept  for  a  long  while. 
For  this  reason  ice  cream  which  has  been  melted  and 
frozen  a  second  time  is  dangerous. 

Toxins,  circulating  among  the  tissues  of  a  living  body, 


THE  RESPIRATION 


127 


may  produce  weakness  and  disease.  Typhoid  fever  is  usu-. 
ally  contracted  through  the  use  of  water  from  an  impure 
source.  There  have  been  cases  of  a  spring  or  well  becom- 
ing infected  with 
typhoid  germs,  and 
giving  typhoid  fever 
to  the  unhealthy 
members  of 
family  that 
water  from  it. 
same  effect 


times     results 


every 
used 
The 

some- 
from 


FIG.  115.  — Well  polluted  with  sewage. 


the  use  of  milk  car- 
ried in  cans  which 
have  been  washed 

in  water  from  an  infected  well  or  stream  (Fig.  115).  It 
requires  many  bacteria  to  produce  infection ;  to  cause 
some  diseases,  severr.l  millions  are  necessary. 

It  has  never  been  proved  that  germs  will  cause  harm  or 
disease  to  a  perfectly  healthy  body.  Some  germs  change 
their  nature  or  the  nature  of  the  toxins  they  form,  according 
to  the  material  iipon  which  they  live  (Fig.  116).  Many 
germs  seem  to  be  harmless  when  living  in  certain  con- 
ditions, but,  if  they  find  a  diseased  condition,  they  seem 
to  change  their  nature  and  begin  the  formation  of  poison- 
ous toxins.  This  is  known  to  be  true  of  the  colon  bacillus, 
and  is  possibly  true  of  typhoid  fever  germs.  Thus  in  many 
cases  it  is  an  impure  body  which  supplies  the  germs  with 
poisonous  food,  and  they  only  return  poison  to  the  body. 

How  Bacteria  are  destroyed  within  the  Body.  —  First,  the 
white  blood  cells  have  it  for  their  chief  function  to  seek  out 
bacteria  and  to  devour  and  destroy  them.  This  explains 
why  many  germs  are  necessary  to  transmit  a  disease. 


128 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


Second,  the  lymph,  the  watery  portion  of  the  blood,  and 
even  mucus  are  able  to  destroy  germs  of  disease.      The 

serum  of  the  blood  often 
contains  a  counter-poison, 
called  an  antitoxin,  which 
poisons  the  germs  and  stops 
their  action.  The  glands  in 
the  neck  (thyroid)  and  over 
FIG.  i i6.  —  a,  germ  destroyed  by  white  the  kidneys  (supra'renal 

blood  cell;  b,  cell  destroyed  by  germs,  ,       x  ,         ,  .,        ,  ,        , 

the  germs  multiplying  and  using  the    Capsules)     and     white     blood 

cell  as  food.  cells  prociuce  antitoxins. 

How  White  Corpuscles  do  their  Work.  —  When  a  blood 
vessel  is  looked  at  under  a  microscope  (see  Exp.,  p.  90) 
the  red  cells  are  seen  floating  along  the  center  in  a  steady 
current  (see  Fig.  117).  Here  and  there  along  the  wall  of 
the  vessel,  transparent  white  corpuscles  will  be  observed. 
These  curious  cells  go  loitering  along  the  wall,  stopping 
now  and  again.  A  ivhite  cell  is  merely  a  little  drop  of  liv- 
ing jelly  with  a  nucleus,  but  without  a  cell  wall.  After  a 
while  the  cell 
comes  upon  a 
little  speck,  a 
germ,  a  particle 
of  medicine,  or 
some  other 
particle  foreign 
to  the  body. 
The  side  of  the 
white  cell 
which  happens 
to  be  next  to 

the  speck  flows  out  on  all  sides  of  the  speck  as  if  it  were 
stretching  out  lips.      Thus  the  germ,  or  speck  is  surrounded 


FIG.  117.  —  BLOOD  VESSEL  with  red  cells  along  the  center 
and  white  blood  cells  leaving  vessel  to  attack  germs  in 
surrounding  tissue. 


THE  RESPIRATION  1 29 

and  carried  off  inside  of  the  cell.  Soon  the  speck  is  dis- 
solved or  digested,  and  disappears.  This  is  occurring  in 
the  body  all  the  time ;  these  little  guardians  are  ever  pro- 
tecting us. 

Boils,  Pimples,  Sores,  etc.  —  Suppose  that  germs  enter 
at  some  tiny  break  in  the  skin.  The  body  is  well  pre- 
pared to  defend  itself  against  them.  The  white  cells  bore 
their  way  through  the  walls  of  tJie  blood  vessels  (p.  133) 
and  come  crowding  around  the  infected  spot.  Soon  a 
white  spot  appears,  and  we  say  the  boil  has  come  to  a 
head.  Then  it  breaks  or  is  lanced,  and  a  mass  of  white 
matter  exudes.  The  microscope  shows  it  to  be  composed 
of  white  cells  that  have  died  while  battling  against  the 
germs  and  destroying  them.  Some  people  regard  pus  as 
impure  matter  taken  out  of  the  blood  in  order  to  purify  it. 
This  is  a  mistake.  It  is  the  remains  of  white  cells  that 
have  lost  their  lives  in  defending  the  body.  The  reason 
that  there  is  not  a  boil  every  time  a  break  in  the  skin 
allows  germs  to  enter,  is  that  usually  the  white  cells  are 
so  vigorous  that  the  germs  are  destroyed  by  the  first  few 
corpuscles  that  reach  the  spot. 

Inflammation.  —  If  the  capillaries  of  any  part  are  weak, 
they  may  be  strained  when  they  are  congested  with  blood 
driven  to  them  by  exposing  the  skin  to  cold.  The  watery 
portion  of  the  blood  exudes  through  the  injured  vessels; 
the  white  blood  cells  collect  to  repair  the  injury  and  the 
part  swells.  When  germs  or  poisons  enter  any  part  of 
the  body,  inflammation  may  occur.  The  place  swells  up,  not 
only  because  the  white  corpuscles  collect  there,  but  because  the 
serum  of  the  blood  is  poured  out  into  the  tissue  to  dilute  the 
poison  and  by  its  antitoxins  destroy  the  germs. 

Need  for  keeping  the  Blood  Pure.  —  If  blood  contains  an 
excessive  amount  of  poison,  the  white  cells  are  weakened 

K 


130  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

and  cannot  defend  the  body.  Once  some  germs  were 
injected  into  the  body  of  a  bird ;  they  did  no  harm  at 
all.  Later,  a  small  amount  of  nicotine  was  injected  in 
the  bird's  blood.  The  germs  were  again  introduced  and 
soon  killed  the  bird.  Alcohol,  opium,  tea",  coffee,  strych- 
nine, arsenic,  calomel,  and  the  poisons  that  pass  into  the 
blood  by  half-digested  food,  likewise  lower  the  resisting 
power  of  the  body.  A  coated  tongue  means  a  low  vital 
resistance ;  the  moldy  growth  on  the  tongue  is  there 
because  the  saliva  is  no  longer  able  to  destroy  germs,  etc. 
The  body  is  in  a  run-down  condition,  or  the  food  tube  has 
been  shamefully  overloaded.  The  saliva  of  a  healthy 
person  will  destroy  germs  and  keep  the  tongue  clean. 
When  the  army  of  white  corpuscles  is  strong,  one  does 
not  take  contagious  diseases.  When  the  army  is  weak  a 
disease  is  readily  taken. 

Germs  alone  cannot  cause  disease.  A  thief  wished  to 
obtain  food  in  a  man's  house.  Three  of  his  friends  bound 
the  watchman,  another  picked  the  lock,  and  the  thief  him- 
self went  in  and  feasted  on  the  food  in  an  overstocked 
pantry.  Did  he  alone  rob  the  house?  If  gluttony,  alco- 
hol, or  tobacco  paralyze  those  watchmen,  the  white  blood 
cells,  if  the  mucous  membrane  or  the  skin  is  weak,  and 
the  germs  enter  and  feed  upon  tissue  already  unsound,  it 
cannot  be  said  that  the  germs  alone  caused  the  disease. 

Diseases  caused  by  Animalcules. — Germs  are  one-celled 
vegetables.  Several  kinds  of  one-celled  animals,  like  the 
ameba,  also  cause  disease.  The  ameba  itself  causes  a 
severe  kind  of  dysentery  if  it  enters  the  intestine  of  man. 
Yellow  fever  is  believed  to  be  caused  by  an  animalcule 
that  lives  as  a  parasite  in  the  bodies  of  a  certain  kind  of 
mosquito.  The  plasmodium,  another  kind  of  parasite 
which  lives  in  certain  species  of  mosquito,  is  believed  to 


THE  RESPIRATION  131 

transmit  malarial  fever.  This  mosquito  has  five  append- 
ages on  its  head  and  alights  with  its  body  held  out  instead 
of  parallel  to  the  supporting  surface.  Malarial  fever  re- 
turns at  somewhat  regular  intervals,  as  each  generation  of 
plasmodia  mature  and  multiply,  setting  free  many  new 
ones  in  the  blood.-  Quinine  taken  just  before  the  fever 
is  due  causes  the  animalcules  to  disappear  from  the  blood. 
Some  scientists  believe  that  it  destroys  them,  others  be- 
lieve that  it  only  causes  them  to  disappear  into  the  bones 
or  the  spleen  or  some  tissue  that  the  quinine  does  not 
reach.  Even  if  the  quinine  cannot  cure  malaria,  it  at 
least  postpones  the  attack  and  gives  the  sufferer,  who  is 
usually  able  to  be  out  of  bed,  a  few  days  of  grace  in 
which  to  strengthen  his  body  by  hygienic  living,  so 

that  his  white   blood   cells   and  his  enriched   blood    can 

• 

destroy  the  plasmodia  and  stop  the  disease.  Whatever  is 
needed,  whether  it  be  purer  water,  simpler  food,  more  tem- 
perate eating,  cold  baths,  or  avoidance  of  stimulants,  will 
be  promptly  adopted  by  people  with  intelligence  and  pru- 
dence enough  to  help  themselves.  Cold  baths  send  the 
blood  bounding  to  the  most  secluded  parts  of  the  tissues •, 
cause  the  blood  cells  to  multiply  rapidly,  and  prevent  mala- 
ria  and  aid  greatly  in  curing  it.  Of  two  sisters  in  a  home, 
one  may  have  malarial  fever,  the  other  may  not.  The  rea- 
son is  that  one  has  some  unhealthful  habit,  such  as  worry- 
ing, fretting,  overeating,  or  idling,  while  the  other  has 
good  habits,  such  as  cheerfulness,  temperate  eating,  indus- 
try, her  blood  is  richer  and  every  germ  transmitted  to  her 
blood  by  the  bite  of  the  mosquito  is  promptly  destroyed. 
Those  who  rely  entirely  on  drugs  to  recover  health  may 
have  to  take  many  doses  in  vain  ;  they  may  become  dys- 
peptic and  constipated  from  calomel,  and  partially  deaf  and 
nervous  wrecks  from  quinine. 


132  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

Cleanliness.  —  Germs  are  everywhere  ;  but  they  are  able 
to  harm  only  weakened  bodies.  Since  it  is  important  that 
the  white  blood  cells  be  not  outnumbered  and  overcome 
by  germs,  cleanliness  is  of  the  greatest  importance.  Con- 
sumptives should  use  paper  for  spittoons,  that  it  may  be 
burned  before  it  dries  and  prevent  the  germs  from  being 
blown  about  in  the  air.  The  excrement  of  typhoid  fever 
patients  should  be  disinfected  with  chemicals  that  destroy 
germs.  Bedding  and  clothing  used  by  persons  while  ill 
with  smallpox  should  be  destroyed,  as  those  germs  pre- 
serve their  vitality  for  years.  Children  with  scarlet  fever, 
measles,  or  other  infectious  diseases,  do  a  great  wrong  if 
they  come  to  school.  A  cistern  for  rain  water  should  be 
cleaned  out  once  a  year,  in  the  autumn  after  the  leaves 
have  fallen. 

FERMENTATION 

The  Nature  of  Fermented  Drinks.  —  The  fact  that  alco- 
holic drinks,  like  wine,  beer,  and  cider,  are  made  from  fruit 
and  grain  suggests  the  false  idea  that  they  are  also  health- 
ful and  nourishing.  Knowledge  of  the  changes  which  fruit 
must  undergo  to  produce  these  liquors  corrects  this  false 
idea.  The  skin  of  fruit  protects  it  from  decay  even  though 
the  yeast  plant  is  on  the  outside  of  this  skin. 

Experiment  29.  With  a  large  microscope  look  at  a 
drop  of  water  in  which  you  have  washed  grapes  or  apples. 
You  may  be  able  to  see  some  little  round  cells,  which  are 
called  " yeast  plants"  because  others  like  them  compose 
bakers'  yeast.  It  is  these  yeast  plants  that  cause  sweet 
fruit  juices  to  change  very  soon  after  they  are  pressed  out. 
See  Fig.  74.  (Photomicrographs.) 

Experiment  30.  If  you  put  a  tablespoonful  of  sugar  into 
the  water  in  which  you  have  washed  some  apples  or  grapes, 


THE  RESPIRATION  133 

and  set  the  glass  in  a  warm  place  for  a  day  or  two,  you 
will  probably  see  tiny  bubbles  rising  in  it.  This  shows 
that  the  sugar  is  changing,  or  fermenting. 

If  you  can  now  look  at  the  yeast  plants  in  the  liquid 
with  a  microscope,  you  will  find  them  growing  and  multi- 
plying. To  support  their  life  and  growth  they  need  oxy- 
gen, and  this  they  are  able  to  get  from  the  sugar  which 
you  put  into  the  water.  In  getting  it  they  cause  the 
sugar  to  break  up  into  two  entirely  different  substances,  — 
carbon  dioxid,  a  gas  which  you  see  as  bubbles,  and  alcohol, 
which  you  do  not  see.  What  is  the  difference  between 
sweet  fruit  juice  when  within  the  fruit  and  cider,  or  wine, 
made  by  pressing  out  the  juice  and  allowing  it  to  ferment  ? 

Beer  making  causes  two  changes  in  the  nature  of  the 
food  originally  in  the  grain.  By  keeping  the  grain  moist 
and  warm  until  it  sprouts,  its  starch  is  changed  to  sugar, 
which  is  soaked  out  with  water  after  the  sprouts  are  killed 
by  heat.  Into  the  sweet  liquid  thus  obtained  yeast  is  put, 
which  soon  changes  the  sugar  in  the  liquid  to  carbon 
dioxid  and  alcohol.  This  liquid,  now  called  beer,  con- 
tains the  same  poison  as  wine  and  cider. 

Why  there  is  Danger  in  Wine,  Beer,  and  Cider.  —  A  poi- 
son may  injure  some  of  the  cells  without  immediately 
causing  the  death  of  the  whole  body.  The  generally 
accepted  definition  of  a  poison  is,  "A  substance  whose 
nature  it  is  when  absorbed  into  the  blood  to  injure  health 
and  destroy  life."  The  amount  of  injury  depends,  among 
other  things,  upon  the  quantity  of  poison  taken  and  the 
ability  of  the  cells  to  resist  it.  Cells  that  are  vigorous, 
well  nourished,  and  healthy  can  resist  poisons  better  than 
those  in  opposite  conditions.  The  most  dangerous  effect 
of  alcoJiol  upon  the  body  as  a  whole  is  that  it  has  the  powei 
to  create  an  almost  irresistible  appetite  for  more. 


134  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

Distilled  Drinks.  —  If  a  vessel  of  water  and  a  vessel  con- 
taining alcohol  are  placed  side  by  side  on  a  stove,  the  alco- 
hol evaporates  much  more  rapidly  than  the  water.  Taking 
advantage  of  this  fact,  fermented  liquids,  which  contain 
much  water,  are  changed  to  distilled  drinks  such  as  whisky 
and  brandy.  After  much  of  the  water  is  evaporated  or 
distilled  away  the  distilled  drink  contains  forty,  fifty,  or 
even  sixty  per  cent  of  alcohol.  Fermented  drinks  contain 
from  five  to  twenty  per  cent. 

EXERCISES  IN  WRITING.  —  The  Hand.  The  Foot.  Right  Habits 
of  Breathing.  Why  Some  Boys  learn  to  Smoke  Cigarettes.  The 
Cigarette  Habit.  Improvement  in  Dress.  Housekeeping.  Why  a 
Certain  Friend  of  mine  has  so  Many  Colds.  A  Story  of  Camp  Life 
and  how  it  affected  Health.  It  is  easier  to  keep  Well  than  to  get  Well. 
How  to  Ventilate  Assembly  Rooms.  Why  I  believe  in  Ventilation. 
A  Friend  who  has  a  Horror  of  Drafts.  How  to  have  Good  Lungs. 
A  Spree.  A  Young  Drinker  who  squandered  his  Inheritance.  Shall 
I  Smoke? 

ALCOHOLIC  REMEDIES  AND  CORRUPT  PERIODICALS. — We  desire 
to  call  attention  to  the  dangerous  character  of  the  hundred  and  one 
largely  advertised  nostrums  which  are  offered  the  public  as  "  Bitters," 
"Renovators,"  "Anti-Chill"  mixtures,  "Catarrh  Cures,"  etc.,  these 
abominable  concoctions  being  harmful  in  direct  proportion  to  their 
alcoholic  or  narcotic  strength. 

A  report  recently  made  gave  the  alcoholic  average  of  all  the  popular 
and  most  widely  advertised  patent  medicines  as  from  ten  to  forty-five 
per  cent  alcohol,  and  if  this  does  not  open  the  eyes  of  physicians  to  the 
gigantic  nature  of  this  evil,  nothing  will.  The  dram  drinker  who  goes  to 
the  saloon  soon  makes  a  wreck  of  himself.  People  who  value  sobriety 
and  steady  nerves  steer  clear  of  the  known  bar  frequenter ;  the  railroads 
keep  an  eye  upon  engineers  and  trainmen,  and  those  who  spend  their 
pay  at  saloons  soon  get  a  chance  to  change  their  vocations.  But  the 
man  who  buys  at  the  drug  store  some  one  of  these  alcoholic  alleged 
"  tonics  "  often  finds  himself  compelled  to  continue  its  use.  His  nerves 
get  shaky,  his  eyes  are  not  as  true  as  they  were,  and  quite  likely  he 
buys  still  more  of  the  same  noxious  stuff,  believing  that  his  stomach 
and  nerves  need  "  fixing."  As  long  as  he  takes  his  tipple  three  times 
a  day  (or  oftener),  he  feels  pretty  well  —  he  is  working  under  alcoholic 


THE  RESPIRATION  135 

stimulation.  Now  let  him  attempt  to  stop  and  he  will  find  he  is  "gone 
to  pieces";  but  none  counts  him  a  "drunkard";  he,  himself,  would 
scout  the  idea. 

The  victims  of  this  alcoholic  nostrum  habit  are  to  be  counted  by 
hundreds  of  thousands ;  mothers  and  thoroughly  good  women  who 
would  die  sooner  than  "  drink  "  take  these  wretched  mixtures  and  find 
a  transient  strength  therein,  which  leads  them  to  "  buy  another  bottle,1' 
with  the  result  that  sooner  or  later  they  are  compelled  to  confinue  the 
habit  or  collapse.  If  the  periodicals  which  advertise  these  drunkard- 
making  medicines  realize  the  damage  they  are  doing,  they  must  be 
edited  and  controlled  by  peculiar  men.  The  religious  press  especially 
offends  decency  and  good  morals  by  exploiting  a  host  of  these  and 
worse  preparations.  And,  to  tell  the  truth,  the  medical  press  is  not  free 
from  taint.  The  temptation  is  perhaps  great  to  accept  a  profitable 
advertising  contract ;  but  when  one  puts  against  the  dollars  gained  the 
ruined  lives  which  must  follow  the  use  of  the  poisons  advertised,  the 
temptation  vanishes. 

The  greater  proportion  of  the  public  after  all  does  not  live  near  the 
saloon,  and  it  is  to  these  country  dwellers  that  the  rum-tonic  men  look 
chiefly  for  their  trade.  —  The  Alkaloidal  Clinic. 

REVIEW  QUESTIONS.  — Chapter  IV.  1.  State  facts  which  show  the 
varied  uses  of  the  muscles.  2.  What  are  the  two  classes  of  muscles? 
3.  Describe  appearance  and  structure  of  voluntary  muscles.  What  are 
the  bundles,  fibers,  and  fibrils?  4.  What  is  the  structure,  position, 
and  use  of  involuntary  muscles?  5.  What  is  (i)  the  structure; 
(2)  the  use,  of  tendons  ?  6.  Describe  the  action  of  the  gullet ;  sphinc- 
ter muscles;  facial  muscles;  calf  muscles;  tailor's  muscle;  flexors; 
extensors.  7.  When  is  the  best  time  for  developing  the  muscles? 
8.  Describe  the  harmonious  action  of  all  the  muscles  when  a  boy 
throws  a  stone.  How  is  this  harmony  made  possible?  9.  Describe 
the  connection  of  a  nerve  with  a  muscle,  and  the  effect  of  one  nerve 
impulse.  10.  What  is  the  source  of  muscular  energy?  11.  How  is 
a  muscle  kept  contracted?  12.  What  is  muscular  tone?  Give  evi- 
dences of  its  existence.  13.  What  causes  fatigue?  14.  Why  does 
rest  relieve  it?  15.  How  is  general  fatigue  caused  by  the  action  of  a 
few  muscles? 

1.  How  does  physical  exercise  aid  the  appetite;  the  circulation? 
2.  What  advantage  have  useful  labor  and  games  over  gymnastics? 
Vice  versa  f  3.  What  kind  of  muscles  belong  to  us  by  inheritance  ? 
Show  why  those  who  try  to  be  healthy  without  exercise  are  attempting 
an  impossibility.  4.  State  the  amount  of  sickness  in  the  United 
States  and  the  chief  causes  of  it.  5.  Show  that  many  persons  do 


136  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

not  use  common  sense  with  reference  to  health.  6.  Show  that  it  is 
never  really  one's  duty  to  neglect  the  health.  7.  How  would  instinct 
guide  in  using  the  muscles?  How  is  this  instinct  usually  disregarded? 

8.  Discuss   exercise   in   different   climates.       9.  Discuss   the   relative 
respect  due  to  physical  and  mental  labor.       10.  Describe  a  better  way 
to  attain  complete  living  than  by  taking  set  exercises. 

REVIEW  QUESTIONS. — Chapter  V.  The  Circulation.  1.  Does  an 
ameba  need  a  circulation?  Why  does  a  man  need  a  circulation? 
2.  State  size,  shape,  and  position  of  the  heart.  3.  Why  must  the  heart 
be  double?  State  the  work  of  each  pump  ;  the  five  parts  of  each  pump. 
4.  Trace  the  blood  in  one  complete  circuit.  5.  Explain  the  structure 
and  use  of  each  of  the  three  coats  in  a  blood  vessel.  6.  Why  must 
the  blood  vessels  be  smooth ;  elastic ;  vary  in  size  from  time  to  time  ? 
7.  Describe  how  a  pulse  wave  travels.  8.  How  may  the  special  sup- 
ply of  blood  furnished  to  any  organ  be  increased;  decreased?  How 
may  more  fresh  blood  be  sent  to  all  the  organs  at  the  same  time? 

9.  Describe    the    capillaries   as    to    structure,    use,   and   blood   flow. 

10.  Describe  the  walls  of  the  veins.       11.  Describe  an  experiment  to 
show  the  effect  of  gravity  on  the  blood  flow ;  to  show  the  working  of 
the  valves  in  the  veins.       12.  What  usually  causes  fainting?    What 
should  be  done  to  aid  recovery?      13.  Give  a  clear  account  of  the 
action  of  the  valves  in  making  the  blood  flow  faster  through  an  actively 
contracting  muscle.       14.  Why  does  faster  blood  flow  from  muscular 
exercise  make  the  heart  beat  faster?      15.  What  is  the  effect  upon  the 
blood  flow  when  the  chest  expands;  contracts?      16.  How  do  exer- 
cise and  physical  labor  strengthen  the  heart?      17.  Why  can  we  not 
blush  or  change  the  beating  of  the  heart  at  will?      18.  What  nerves 
increase  the  heart  beat ;  what  decrease  it?      19.  How  does  the  heart 
obtain  nourishment  from  the  blood? 

1.  The  microscope  shows  the  blood  to  possess  what  parts? 
2.  What  is  each  part  for?  3.  What  is  meant  by  the  pulmonary  cir- 
culation;  the  systemic  circulation;  arterial  blood;  venous  blood? 

4.  Describe  the  three  purifications  of  the  blood.       5.  Describe  the 
process  called   coagulation.     Of  what  use  is  it?      6.  Compare  veins 
and  arteries  in  the  following  points  :  walls  ;  closing  when  cut ;  position ; 
color;  flow  of  blood;  where  they  begin  and  empty. 

1.  Of  what  does  the  lymphatic  system  consist?  2.  What  is  the 
appearance  of  lymph?  Where  have  you  seen  it?  3.  Why  are  lymph 
spaces  necessary?  4.  What  is  the  function  of  the  lymphatics? 

5.  How  does  (i)  carbon  dioxid,  (2)  other  waste  materials,  (3)  unused 
food,  go  from  the  lymph  spaces  into  the  blood  ?      6.  Which  circulatory 
system  has  neither  beginning  nor  ending ;    both  beginning  and  end- 


THE  RESPIRATION  137 

ing?  7.  Into  how  many  vessels  do  the  lymphatics  finally  unite? 
Give  their  names.  Into  what  do  they  empty?  8.  What  is  dropsy? 
9.  What  and  where  are  the  lacteals?  10.  State  several  ways  in 
which  the  lymph  is  made  to  flow.  11.  What  is  the  function  of  the 
lymph  glands?  12.  What  is  the  origin  of  the  white  corpuscles? 
13.  What  is  the  function  of  the  spleen?  14.  Show  that  the  blood 
is  more  necessary  to  life  than  are  the  nerves.  15.  What  is  the  great- 
est benefit  from  muscular  exercise?  16.  Show  the  fallacy  of  a  "blocd 
purifier."  17.  Describe  the  direct  and  indirect  effects  upon  the  skin 
of  an  improved  circulation ;  upon  fat ;  upon  the  muscles ;  skeleton ; 
brain ;  lungs ;  heart ;  stomach.  18.  Discuss  thin  blood  (anemia) ; 
how  it  comes;  how  avoided.  19.  Where  do  red  blood  cells  begin? 

REVIEW  QUESTIONS.  —  Chapter  VI.  1.  How  are  the  lungs  con- 
structed so  as  to  increase  the  surface  for  absorbing  oxygen?  2.  What 
are  the  three  stages  in  respiration?  3.  What  cavity  is  behind  the 
mouth  and  nasal  passages?  4.  What  tubes  open  into  the  pharynx 
from  below?  Which  one  has  a  lid?  5.  What  is  the  structure  of  the 
trachea?  6.  Describe  the  branching  of  the  trachea?  7.  What  is  a 
bronchial  tube;  lobule;  air  cell?  8.  What  are  cilia?  9.  Describe 
the  lungs ;  the  pleura.  10.  Name  the  chief  breathing  muscles. 
11.  Describe  the  position  of  the  diaphragm.  12.  How  do  the  chest 
walls  and  floor  move  during  inspiration?  Why  does  the  air  go  in? 
Why  do  the  lungs  expand  with  the  chest?  13.  What  causes  the  dia- 
phragm to  ascend  during  expiration?  Why  cannot  the  diaphragm 
press  upward  without  being  lifted  by  the  organs  below?  14.  When 
and  how  does  expiration  occur  without  muscular  effort?  15.  Discuss 
chest  breathing,  abdominal  breathing,  and  full  breathing.  Which  is 
the  natural  way?  Why  should  no  discussion  ever  have  arisen  regard- 
ing it?  16.  What  are  the  disadvantages  of  the  other  methods? 
17.  Why  is  a  person  with  flabby  abdominal  walls  likely  to  have  a  stag- 
nant liver?  (p.  87.) 

1.  Describe  three  experiments  to  show  the  changes  which  the  air 
undergoes  in  the  lungs.  2.  What  is  the  origin  of  "crowd  poison"? 
3.  What  is  said  of  bad  ventilation  in  assembly  rooms?  4.  Discuss 
dust;  sweeping;  dusting.  5.  Which  methods  of  heating  allow  best 
ventilation?  6.  Why  should  a  stove  always  be  near  a  window? 
7.  State  the  reasons  for  breathing  through  the  nose.  8.  Describe 
how  the  lungs  and  air  passages  are  affected  in  the  several  diseases 
mentioned.  9.  Discuss  the  prevention  of  colds  and  lung  troubles. 


CHAPTER  VII 
FOOD  AND  DIGESTION 

The  Uses  of  Food ;  Heat.  —  The  body  keeps  at  a  tempera- 
ture of  98.6°  in  the  coldest  weather.  The  temperature 
of  the  Eskimo  boy  living  in  the  frigid  zone  is  the  same 
as  the  temperature  of  the  negro  living  in  the  torrid  zone. 
The  interior  of  our  bodies  is  as  warm  on  the  coldest 
winter  day  as  in  summer.  The  source  of  the  heat  is  the 
burning  of  the  food  which  we  eat  by  the  oxygen  wJiich  we 
breathe. 

Work.  —  A  horse  does  work  when  he  draws  a  wagon. 
An  engine  does  work  when  it  moves  a  train  of  cars,  or 
even  when  it  moves  itself.  Our  bodies  are  capable  of 
moving  and  of  exerting  force.  To  exert  force  or  to  do 
work  uses  energy.  What  is  the  source  of  this  energy  ? 
Its  source  is  likewise  the  burning  of  the  food  by  the  oxygen. 

Growth.  —  The  body  of  a  young  person  grows,  or  is 
built  up,  cell  by  cell.  The  cells  obtain  not  only  the 
material,  but  the  strength,  or  energy,  necessary  for  build- 
ing the  body,  from  the  food  and  oxygen.  Hence  the 
uniting  of  food  and  oxygen  in  the  body  is  a  source  of  heat, 
work,  and  growth. 

The  Steps  in  Nutrition. — After  being  eaten  the  food 
must  first  be  made  soluble  that  it  may  be  carried  by  the 
blood.  This  change  is  called  digestion.  When  the  blood 
and  lymph  bring  the  food  in  reach  of  the  cells,  the  cells 
absorb  it  and  change  it  into  material  like  themselves. 

138 


FOOD  AND  DIGESTION  139 

This  process  is  called  assimilation  or,  in  simple  English, 
"a  making  like."  The  activity  of  the  cells  by  which  the 
burning  takes  place  and  the  compound  substance  is  broken 
down  into  carbon  dioxid,  water,  and  urea  is  called  oxida- 
tion. The  ridding  of  the  body  of  the  products  of  oxidation 
is  called  excretion.  Food  is  sometimes  called  nourishment. 
The  combined  action  of  all  the  organs  concerned  in  nourish- 
ing the  body  is  a  process  called  nutrition. 

Energy  cannot  be  destroyed,  although  one  form  of  energy 
can  be  changed  to  another  kind.  By  rubbing  a  coin  on 
the  table,  muscular  energy  produces  motion,  which  in  turn 
produces  heat,  for  the  coin  will  become  very  hot. 

The  Bodily  Furnace  and  the  Storing  of  the  Fuel.  —  More 
or  less  motion  of  the  body  or  some  of  its  parts  is  constantly 
taking  place ;  heat  is  constantly  escaping  from  the  body ; 
the  tissues  are  constantly  being  repaired.  The  energy  to 
replace  that  which  is  lost  comes  from  the  oxidation  of 
the  food.  Not  all  of  the  food,  when  absorbed  from  the 
food  tube,  enters  the  active  cells,  but  some  of  it  is  de- 
posited in  storage  cells  called  fat  cells.  This  is  like  coal 
banked  up  in  the  furnace,  which  the  fire  has  not  yet 
reached.  In  our  bodies  the  furnace  is  in  the  cells  ;  wherever 
there  is  living  tissue,  the  contents  of  the  cells  are  being 
burned  to  enable  the  tissue  to  live  and  to  work. 

Different  Forms  cf  Burning.  —  To  a  chemist  anything  is 
burned  when  it  unitec  with  oxygen.  If  the  burning  takes 
place  at  great  heat  and  very  rapidly,  it  is  called  combus- 
tion. There  is  no  combustion  in  the  body.  TJie  oxidation 
in  the  body  takes  place  not  only  at  a  low  temperature,  but  in 
the  presence  of  moisture.  The  rusting  of  iron  and  the  rotting 
of  a  tree  are  examples  of  oxidation  that  is  aided  by  moisture. 
Yet  the  same  amount  of  heat  is  set  free  by  the  slow  rotting 
of  a  tree  as  would  have  been  set  free  by  burning  it  in  a 


140  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

furnace.  In  the  first  case  the  heat  set  free  is  carried  off 
nearly  as  fast  as  it  appears.  In  the  second  case  the  heat 
is  given  off  in  a  much  shorter  time.  Rotting  and  rusting 
are  even  slower  than  the  oxidations  that  take  place  in  our 
bodies. 

Amount  of  Energy  set  free  in  the  Body.  —  One  of  the 
chief  kinds  of  energy  set  free  in  the  body  is  heat.  The 
amount  about  equals  that  produced  by  the  continuous 
burning  of  two  ordinary  candles.  The  body  is  a  power- 
ful machine,  and  is  capable  of  expending  a  great  deal  of 
energy  in  the  form  of  work.  The  amount  of  work  that 
the  body  can  do  in  a  day  has  been  carefully  estimated. 
It  is  equal  to  lifting  its  own  weight  a  foot  high  every 
second  for  twenty-four  hours.  One  seventh  of  this  work 
is  done  by  the  heart.  About  an  equal  amount  of  work  is 
performed  in  the  movements  of  breathing.  The  remainder 
of  the  work  is  done  by  the  other  muscles  of  the  trunk  and 
limbs,  and  by  the  involuntary  muscles  of  the  food  tube. 
The  energy  expended  in  the  process,  growth,  has  not  yet 
been  accurately  estimated. 

The  Body  as  a  Machine.  —  A  working  steam  engine  is 
warm  because  of  the  fire  in  the  furnace ;  so  our  bodies  are 
warm  because  of  the  oxidation  in  the  cells.  The  heat  is 
distributed  through  the  body  by  the  blood. 

The  body  has  many  parts  which  correspond  to  the  parts 
of  machines.  There  are  the  bones  which  act  as  levers,  the 
hinge  joints,  the  pivot  joints  which  resemble  the  action  of 
a  wheel.  The  blood  vessels  resemble  hollow  pipes.  There 
are  hollow  tubes  which  give  strength  with  lightness,  as  do 
the  hollow  tubes  on  a  bicycle  frame.  Name  some  of  the 
hollow  bones. 

How  Energy  is  stored  in  Food.  —  The  energy  of  the  food 
comes  from  the  sun  and  it  is  stored  up  by  the  sunlight. 


FOOD  AND  DIGESTION 


141 


CarbonicNVcid  Gu 
in  the  Air  going 
into  the  Leal 


No  plant  grows  in  the  dark  except  the  simple  plants  like 

mushrooms,  which  get  their  food  by  living  upon  decaying 

plants.    All  animals  live  upon  plants.    Those  animals  which 

live  upon  other  animals  are,  of  course,  indirectly  feeding 

upon  plants.      The  plants,  aided  by  the  sunlight,  store  tip 

starch,    sugar,    oil,    and    albumin. 

Tlie  leaves  of  plants,  by  separating 

the  oxygen  from  carbon  in  carbon 

dioxid,  and  giving  off  the  oxygen 

through  their  pores,  prepare  the  air 

for  us  to  breathe  (see  Fig.   118). 

The  force  to  do  this  comes  from 

the   sun ;    only  green   leaves   can 

accomplish  it,  and  leaves  must  grow 

in  the  light  in  order  to  be  green. 

It  is  impossible  for  an  animal  to 

gather  up  energy  from  the  sunlight 

and  store  it  away ;   fortunately,  it 

is   also  impossible   for  the   plants 

to  use  up  the  energy  which  they 

gather.     They  use  a  little  of  this 

energy  in  growing,  but  they  cannot  use  it  in  moving,  or 

in   keeping  themselves  as  warm  as  animals.      Birds  fly ; 

some  seeds  of  plants  have  wings,  but  they  cannot  fly  unless 

borne  by  the  energy  of  the  wind.     Plants  store  up  energy ; 

animals  expend  it. 

The  Four  Kinds  of  Food  Stuffs. — The  kinds  of  food 
which  we  eat  seem  to  be  numberless,  but  they  contain  only 
four  kinds  of  food  stuffs,  —  starches,  fats,  proteids,  and 
minerals.  Many  foods  contain  all  four  classes  of  food 
stuffs.  Milk  contains  sugar  (a  changed  form  of  starch), 
cream  (a  fat),  casein  (a  proteid),  and  water.  Oatmeal  con- 
tains starch,  oil,  gluten,  and  water. 


FIG.  us. 
BLACKBOARD  DIAGRAM. 

The  plant  taking  in  carbonic  acid 
gas,  called  also  carbon  dioxid, 
produced  by  burning  or  animal 
life.  Aided  by  the  sun's  rays, 
the  leaf  builds  the  carbon  into 
starch,  wood,  etc.,  and  gives  back 
the  oxygen  to  the  air. 


142 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


TABLE  OF  FOOD  STUFFS 

1.  Proteids,  the  building  foods  (also  of  value  as  fuel). 

2.  Starches  (and  sugars)  1  „ 

3.  Fats  (and  oils)  j  Energy  and  heat  Producm§  foods' 

4.  Minerals  (water,  salt).    Important  aids  in  using  other  foods. 

Starch  and  the  sugars  are  closely  related ;  indeed,  starch 
readily  changes  into  sugar.  They  contain  much  carbon  and 
are  called  carbohydrates.  Starch  is  especially  abundant  in 
grains,  seeds,  and  fleshy  roots  (Fig.  1 19).  Sugar  in  ripe  fruit 

and  in  honey  is  called 
fru it  sugar.  Milk  sugar 
is  found  in  sweet  milk. 
Grape  sugar  is  found  in 
grapes  and  honey ;  the 
small  grains  seen  in  rai- 
sins consist  of  grape 
sugar ;  it  can  also  be 
prepared  artificially  from 
starch.  Cane  sugar  is 
found  in  cane  and  in  the 
sugar  beet. 

Experiments.  —  31.  A 
few  cents'  worth  of  tinc- 
ture of  iodine  from  the 
drug  store  will  enable 
the  teacher  to  show  the  tests  for  starch  and  proteid.  A  por- 
tion of  the  iodine,  diluted  with  water  to  a  light  brown  color, 
causes  the  starch  in  potato,  grain,  etc.,  to  turn  blue.  Do 
fleshy  leaves,  stems,  and  wood  contain  starch.  32.  Strong 
iodine  will  cause  the  proteid  of  grain,  potato,  etc.,  to  turn 
brown. 

Fats  include  the  fats  and  oils  found  in  milk,  flesh,  and 
plants.  A  fat,  such  as  tallow,  is  solid  at  the  ordinary 


FIG.  119.  — A  TINY  BIT  OF  POTATO,  highly 
magnified,  showing  cells  filled  with  grains 
of  starch.  See  Fig.  140. 


FOOD  AND  DIGESTION  143 

temperature ;  while  an  oil,  such  as  olive  oil,  is  liquid  at 
the  same  temperature.  Tallow  was  oil  while  it  was  in 
the  warm  body  of  the  ox.  Fats  and  oils,  although  so 
different  in  taste  from  starch  and  sugar,  are  composed 
of  the  same  three  chemical  elements,  but  they  are  com- 
bined in  different  proportions. 

Proteids  are  the  only  foods  that  contain  the  tissue-build- 
ing nitrogen.  We  do  not  often  see  a  pure  proteid  food, 
for  this  food  stuff  is  not  so  readily  separated  from  foods 
containing  it  as  are  starch,  sugar,  and  fat.  Albumen,  or 
white  of  an  egg,  is  proteid  mixed  with  four  times  its 
weight  of  water.  Pure  proteid,  or  albumin,  readily  coagu- 
lates when  heated,  and  in  this  way  it  is  easily  recognized 
by  chemists.  These  are  the  names  of  proteids,  or  albu- 
mins, found  in  several  common  foods:  casein,  the  curd  or 
cheesy  part  of  milk  ;  myosin  of  lean  meat ;  fibrin  in  blood ; 
Icgumen  in  beans  and  peas ;  gluten,  or  the  sticky  part  of 
wet  flour ;  albumen,  or  the  white  of  an  egg ;  gelatin  in 
bones.  Remember  that  proteid  is  valuable  to  the  body 
as  fuel  as  well  as  a  tissue  builder.  We  could  burn  beans 
and  peas  as  well  as  the  strictly  fuel  foods,  starch  and  fat, 
in  an  engine,  and  get  heat  to  move  the  engine. 

Minerals.  —  The  body  is  about  two  thirds  water.  The 
cells  must  do  all  their  work  under  water.  They  cannot 
live  when  dried.  Water  enables  the  blood  to  flow  ;  and  the 
blood  is  not  only  the  feeder,  but  also  the  washer  and 
cleanser  of  the  tissues.  Some  persons  get  out  of  the 
habit  of  drinking  plenty  of  water,  and  their  health  suffers 
thereby.  If  such  a  person  will  drink  two  tumblers  of 
water  upon  rising,  three  an  hour  or  two  before  dinner, 
the  same  before  supper,  and  two  upon  retiring,  or  ten 
tumblers  (amounting  to  two  quarts)  each  day,  he  will 
probably  find  himself  restored  to  perfect  health.  Watery 


144  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

foods  and  fluids  taken  at  meals  will  reduce  the  amount  of 
water  drunk  at  other  times,  but  it  is  best  to  observe 
moderation  in  taking  fluids  at  meals.  Common  salt  is  used 
by  all  races,  but  it  is  used  least  by  the  Eskimos  and  others 
that  live  chiefly  upon  meat.  It  is  needed  most  by  lower 
animals  and  men  that  live  chiefly  upon  plants  for  food. 

Wastes.  —  It  is  clear  that  the  body  must  return  daily  to 
the  outside  world  about  as  great  a  weight  of  material  as  it 
receives  from  it.  The  wastes  of  the  body  result  from 
oxidation  in  the  tissues ;  they  consist  of  carbon  dioxid gas, 
a  white  solid  called  urea,  and  water.  The  first  is  given  off 
by  the  lungs,  the  second  by  the  kidneys,  and  the  last  by 
both  lungs  and  kidneys.  These  wastes  are  very  simple 
compounds  compared  to  sugar,  fats,  and  proteids,  which 
are  very  complex  substances,  built  up  by  the  green  matter 
in  plants,  aided  by  the  sunlight.1  The  animal  body  has 
not  the  constructive  power  of  the  plant ;  it  can  only  tear 
down  what  the  plant  has  built  up.  The  three  physiological 
wastes  mentioned  are  the  result  of  vital  processes.  Another 
kind  of  waste  consists  of  refuse  materials,  as  wood  fiber  in 
green  vegetables,  rejected  by  the  alimentary  canal. 

Sources  of  Food.  —  All  parts  of  a  plant  may  furnish  food: 
the  seed,  as  the  various  grains,  nuts,  and  fruits ;  leaves,  as 
lettuce,  cabbage,  dandelion ;  roots  and  tubers,  as  potatoes 
(Fig.  119),  beets,  turnips,  tapioca  (root  of  cassava);  stem, 
as  sago  (pith  of  sago  palm);  saps,  as  sugars  (of  cane, 
beets,  and  maple  tree);  honey,  and  oils  (from  peanuts, 
cotton  seed,  olives,  pecans,  and  other  nuts).  Food  from  an 
animal  source  may  consist  of :  flesh,  as  beef,  mutton,  veal ; 
milk,  with  its  products,  as  butter  and  cheese  ;  eggs  of  birds. 
Salt,  one  of  the  two  chief  mineral  foods,  is  obtained  from 

1  The  chemical  formula  for  water  is  H2O,  for  carbon  dioxid,  CO2  ;  but  the 
chemical  formula  for  protoplasm  is  about 


FOOD  AND  DIGESTION  145 

mines  and  wells ;  water  is  obtained  from  springs,  wells, 
lakes,  rivers.  It  is  of  the  very  highest  importance  that 
water  should  be  pure  and  uncontaminated  with  vegetable 
or  animal  matter. 

The  Daily  Ration.  —  A  quarter  of  a  pound  (4  oz.)  of 
proteid  foods  and  one  pound  (16  oz.)  of  fuel  foods  are 
needed  to  replace  the  daily  waste  of  the  body.  The 
twenty  ounces  of  food  to  make  the  ration  for  one  day 
are  reckoned  on  the  basis  of  dry  or  water-free  foods.  It 
is  seen  that  the  two  kinds  of  foods  are  needed  in  the  pro- 
portion of  one  to  four  (4  oz.  to  16  oz.). 

Limits  to  Scientific  Regulation  of  Diet.  —  It  is  impossible 
as  well  as  undesirable  to  select  food  so  as  to  regulate  the 
diet  according  to  exact  calculations  of  their  composition. 
If  possible  to  do  so,  it  would  cost  an  immense  amount  of 
labor  and  care.  Appetite  is  a  perfect  guide  for  those  who 
lead  an  active  life  and  eat  simple  food.  Highly  seasoned 
food  and  complex  mixtures  deprave  the  appetite ;  it  then 
leads  astray,  instead  of  guiding  safely.  Of  course  the 
appetite  cannot  guide  one  to  eat  the  right  kind  and 
quantity  of  food  at  a  table  where  the  food  lacks  any  of  the 
four  necessary  food  stuffs,  or  where  innutritious  or  in- 
digestible food  is  provided. 

One  extreme  is  where  housekeepers  are  so  ignorant  as 
not  to  know  the  difference  between  a  proteid  and  a  fuel 
food ;  the  other  is  where  the  diet  is  regulated  without 
reference  to  the  taste  of  the  consumer.  The  moderate 
course  is  for  every  intelligent  person,  especially  every 
housekeeper,  to  study  the  proper  proportions  of  food,  and 
to  calculate,  with  the  aid  of  tables,  the  proper  combi- 
nations of  all  foods  commonly  used,  thus  acquiring  a 
general  idea  of  food  values  (see  pp.  147,  174);  then  to  be 
guided  in  selecting  the  bill  of  fare  by  both  the  appetite  and 


146  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

these  general  ideas.  Intelligence  in  regard  to  diet  enables 
a  housekeeper  to  provide  nourishing  food  for  less  money 
than  an  ignorant  housekeeper  often  pays  for  food  deficient 
in  nourishing  qualities  (see  Fig.  138,  p.  1/4). 

How  to  select  a  Balanced  Ration.  —  It  is  most  essential 
to  provide  the  right  amount  of  proteid  (4  oz.);  nor  should 
any  great  excess  of  this  amount  be  eaten.  Sufficient  fat 
(2  oz.)  should  also  be  provided.  Sugar  and  starches  are 
found  in  so  many  foods  that  a  lack  of  them  in  the  food  is 
not  probable,  nor  is  an  excess  of  them  likely  to  do  much 
harm.  A  deficiency  of  starch  may  be  supplied  by  an 
excess  of  fat  or  sugar.  It  is  impossible  to  replace  proteid 
by  any  other  food  stuff.  The  table  on  page  147  shows  the 
fraction  of  an  ounce  of  each  element  contained  in  an  ounce 
of  each  of  the  foods  shown. 

To  obtain  the  required  daily  amount  (4  oz.)  of  proteid 
from  beans  alone,  16  oz.  of  beans  must  be  eaten,  for  i  oz. 
of  beans  contains  only  .25  oz.  (J  oz.)  of  proteid  (see  Table). 
This  amount,  of  course,  would  not  be  relished.  To  obtain 
the  amount  from  lean  beef,  20  oz.  must  be  eaten,  since 
i  oz.  of  lean  beef  contains  only  .20  oz.  (^  oz.)  of  proteid 
(see  Table).  By  using  half  of  the  above  weights  of  beans 
and  beef,  you  would  take  half  of  the  needed  proteid  in  the 
form  of  beans,  and  one  half  in  the  form  of  beef.  The 
8  oz.  of  beans  would  also  furnish  4  oz.  of  starch  (see  Table). 
The  remainder  of  the  starch  needed,  as  well  as  the  fat, 
would  have  to  be  obtained  from  other  foods. 

Suppose  you  wish  to  arrange  a  ration  with  three  foods. 
The  simplest,  though  not  the  most  accurate,  way  would  be 
(with  due  consideration  to  taste  and  digestion)  to  select 
one  of  the  foods  because  it  is  rich  in  proteids,  another 
because  it  is  rich  in  fat,  and  the  third  because  it  is  rich 
in  starch  or  sugar. 


FOOD  AND  DIGESTION1 


147 


COMPOSITION  OF  ONE  OUNCE  OF  VARIOUS  FOODS  IN  FRACTIONS 
OF  AN  OUNCE 


PRO- 

TEIDS 

FATS 

CARBOHY- 
DRATES 

WATER 

MINERAL 
SALTS 

WOODY 
FIBER 

Daily  Ration 
I.  NUTS. 
Pecan  

40Z. 

•  IO1 

2  OZ. 

.708 

14  OZ. 
.147 

2  qts. 

.07, 

OI7 

O 

Walnut      .... 
Almonds   .... 
Cocoanut  .... 
Chestnut  .... 

II.  FRUITS. 
Peach  

.158 

•235 
.056 

•°37 
007 

•574 
•53 
•5* 

.02 

.16 
.12 

•38 

Sugar 

O4.C 

•03 
.078 

•35 
•54 

8s 

.014 
.009 

OO7 

.04 
.02 

OA 

.004 

•'•"O  . 
O72 

•"3 

84. 

**»/ 

ooc 

**T 

OC 

Blackberry     .     .     . 
Cherry       .     . 

.005 
ooc 

.040 
IO 

.86 
8d. 

*M/3 

.004 
OO7 

•WJ 
.01 
02 

Grape  

*M*3 

.I2C 

I  c 

70 

A*vy 

OOC 

Fig  (dried)    .     .     . 
Banana     .... 

III.  ANIMAL  FOOD. 
Lean  beef     .     .     . 
Fat  pork    .... 
Smoked  ham      .     . 
Whitefish  .... 
Poultry     .... 
Oysters      .... 
Cow's  milk     .     .     . 
Eees 

.040 
.050 

.20 

.098 
.25 
.l8l 
.210 
•175 
•035 
.I2C 

.OI4 

•035 
.489 

.365 
.029 
.038 
.005 
.040 
.I2O 

••3 

•50 
.20 

.009 
.040 

./«-» 

•75 

•75 
•390 
.278 
.780 
.740 
.800 
.870 

.771: 

•*-"O 

.016 

.023 

.101 
.010 

.012 

.015 

.007 

oOIO 

Cheese      .... 
Butter  

IV.  PODS  OR  LEGUMES. 

•335 
.003 

.2C 

•243 
.910 

.O2O 

Starch 

,C2 

•368 

.060 

.I2C 

.054 

.021 

.O7C 

.060 

Peas     

.217 

.OI9 

.C77 

.12 

.028 

.0^2 

Peanuts     .... 

V.  GRAINS. 
Wheat  flour  (white) 
Wheat  bread      .     . 
Oatmeal    .... 
Maize  (corn)      .     . 
Rice     

.2947 

.110 

.080 
.126 
.100 

.oco 

.465 

.020 
.015 
.056 
.067 
.008 

O// 
.162 

.703 
.490 
.630 
.706 
.832 

.02 

.150 
.400 
.150 

•135 
.IOO 

.028 

.017 
.012 
.030 
.014 
.OOC 

.043 

.003 

.003 

.016 

.015 

•O4.O 

VI.  VEGETABLES. 
Potatoes   .... 
Cabbage    .... 

.012 
.02' 

.001 

.030 

.205 
.058 

.767 
.910 

.009 
.007 

.006 
.015 

148  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

Studies  based  on  Table.  —  What  nuts  are  richest  in 
prcteids  ?  What  fruits  ?  What  animal  foods  ?  What 
legume  ?  What  grains  ?  What  foods  are  richest  in  fats  ? 
What  are  richest  in  carbohydrates  ?  Which  grain  has 
most  starch?  Which  nut?  Which  fruit  has  most  sugar? 
A  family  was  living  chiefly  on  corn  bread,  potatoes,  butter, 
sirup,  cakes,  and  sweetmeats :  what  food  stuffs  were 
deficient  in  their  diet  ?  Another  family  lived  chiefly  on 
fat  pork,  bread,  rice,  vegetables,  and  fruit :  which  food 
stuff  was  deficient  ?  A  man  tried  to  live  on  pecans,  bread, 
fruit,  and  vegetables  :  which  food  stuff  was  deficient  ?  If 
he  had  substituted  lean  beef  for  pecans,  which  food  stuff 
would  have  been  deficient  ?  If  he  had  substituted  chest- 
nuts for  pecans,  what  two  food  stuffs  would  have  been 
deficient  ?  Why  would  almonds  have  balanced  the  diet, 
although  beef  and  chestnuts  failed  in  turn  ?  Construct  a 
balanced  ration  of  beef,  butter,  and  wheat  bread.  Con- 
struct one  of  beans,  rice,  and  fat  pork.  Construct  one  of 
poultry,  potatoes,  oatmeal,  cabbage,  almonds,  peaches. 
Select  smoked  ham,  flour,  beans,  and  bananas  for  one  day. 

Would  it  be  cheaper  to  increase  the  smoked  ham  and 
decrease  the  beans  in  the  above  ration,  or  the  reverse  ? 
(See  table,  p.  174.)  What  weights  of  each  food  will 
be  needed  if  the  meals  are  prepared  for  five  persons 
instead  of  one  ?  Why  do  bread  and  butter  make  a  ration 
of  about  the  right  proportions  ?  If  a  farmer  has  no  money 
to  buy  meat  and  bread,  can  he  substitute  beans  and  pota- 
toes and  still  supply  his  family  with  enough  of  each  food 
stuff  ?  Why  is  meager  food  for  a  nation  or  a  person  poor 
economy  ?  Why  is  rich  food  or  a  large  variety  of  food 
often  a  great  misfortune  ? 

How  the  Right  Proportions  of  Fuel  Foods  and  Proteid 
are  reached  by  Different  Nations.  —  Milk  has  an  excess  of 


FOOD  AND  DIGESTION  149 

nitrogen,  and  oatmeal  an  excess  of  carbon  ;  oatmeal  and 
milk  form  a  perfect  food,  and  it  is  not  surprising  that  a 
whole  nation  (the  Scotch)  have  lived  upon  it  and  thrived. 
Potatoes  are  mostly  starch  and  water ;  the  starch  in  them 
is  more  than  four  times  as  much  as  the  proteid,  and  an 
Irishman  who  tried  to  live  on  potatoes  alone  would  have 
to  eat  seven  pounds  a  day  to  get  enough  proteid.  Every 
Irish  peasant  is  said  to  keep  a  cow  and  chickens ;  by 
eating  milk  and  eggs  also  he  can  get  along  on  half  the 
amount  of  potatoes  named  above.  The  Mexicans  eat 
bread  made  of  corn  meal,  and  supply  the  proteid  by  using 
beans  as  a  constant  article  of  diet.  The  Zulus  live  on 
cracked  corn  by  adding  milk  to  it.  The  Arabs  live  on 
barley  and  camels'  milk,  rarely  eating  the  camels'  flesh. 
Hundreds  of  millions  of  people  in  Asia  (the  Hindoos, 
Chinese,  and  others)  subsist  mainly  on  rice,  which  con- 
tains only  six  per  cent  of  proteid  and  no  fat ;  the  chief 
addition  they  make  is  butter,  or  other  fat,  and  beans,  which 
contain  vegetable  proteid. 

Outline  of  Digestion.  —  The  food  is  made  soluble  in 
the  alimentary  canal  and  is  absorbed  by  the  blood  vessels 
and  lymphatics  in  its  walls.  This  canal  is  about  thirty 
feet  long  (Fig.  125)  and  consists  of  — 

(1)  The  mouth,  where  the  food  remains  about  a  minute, 
while  it  is  chewed  and  mixed  with  the  saliva ;  the  saliva 
changes  a  portion  of  the  starch  to  malt  sugar. 

(2)  The  gullet,  a  tube  nine  inches  long,  running  from 
mouth  to  stomach  and  lying  in  front  of  the  spinal  column. 

(3)  The  stomach,  a  large  pouch  where  the  food  is  stored, 
and  from  which  it  passes  in  the  course  of  several  hours, 
having  become  semiliquid,  and  the  proteids  having  been 
partly  digested  by  \he  gastric  juice,  an  acid  secretion  from 
the  small  glands  in  the  stomach  walls. 


ISO 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


(4)  The  small  intestine,  a  narrow  tube  more  than  twenty 
feet  long,  where  the  fats  are  acted  upon  for  the  first  time, 
and  where  the  starches  and  proteids  are  also  acted  upon, 
and  where,  after  about  ten  hours,  the  digestion  of  the 
three  classes  of  foods  is  completed  by  pancreatic  juice 

from    the   pancreas,    and    bile 
from  the  liver  (Fig.   120). 

(5)  The  large  intestine,  about 
five  feet  long,  where  the  last 
remnant  of  nutriment  is  ab- 
sorbed, and  the  indigestible  ma- 
terials in  the  food  are  gathered 
together. 

The  Absorption  and  Assimi- 
lation of  Food.  —  Take  a  piece 
of  bread  in  your  hand.  It  be- 
longs to  you,  but  it  is  not  a 
part  of  you.  Put  it  into  your 
mouth  and  chew  it.  Still  it  is 
not  a  part  of  you.  It  becomes 
mixed  with  the  saliva  and 
partly  digested.  You  swallow  it  and  it  is  now  in  your 
stomach.  Still  it  is  not  a  part  of  you.  Little  by  little 
the  portal  vein  absorbs  the  dissolved  bread  and  carries 
it  to  the  liver,  where  it  is  converted  into  liver  starch 
to  be  stored  until  it  is  needed.  Still  it  is  not  a  part 
of  you. 

From  the  liver  the  dissolved  bread  finally  finds  its  way 
into  the  general  circulation.  But  it  is  not  yet  a  part  of 
you.  Having  circulated  through  the  blood  vessels,  it 
passes  from  vessel  to  vessel,  smaller  and  smaller,  until 
it  finally  reaches  the  capillaries.  Still  the  dissolved  bread 
is  not  a  part  of  you.  It  now  oozes  out  through  the  walls 


Vermiform   . 
Appendix 


FIG.  120.  —  FOR  BLACKBOARD. 


FOOD  AND  DIGESTION  I$I 

of  the  capillaries  into  the  lymph  spaces,  surrounding  and 
permeating  every  tissue.  And  yet  it  can  hardly  be  said  to 
be  a  part  of  you. 

In  every  tissue  each  one  of  the  millions  of  living  cells  is 
capable  of  absorbing  to  itself  a  minute  quantity  of  the 
nutritive  juices  which  touch  it.  Each  of  these  cells  takes 
something  from  the  lymph,  taking  only  the  portion  that  it 
needs,  leaving  the  other  portions  for  other  tissues.  It  is 
only  when  these  minute  cells  have  taken  the  food  from  the 
lymph  and  assimilated  it  that  the  digested  bread  actually 
becomes  a  part  of  you. 

Very  soon  the  cells  will  discard  the  food  in  another  form 
as  waste  material.  Some  of  it  will  be  taken  up  again  by 
the  capillary  vessels,  but  the  most  of  it  will  be  taken  up 
by  the  lymphatics.  The  lymphatic  vessels  convey  this 
used  material  back  into  the  venous  blood  vessels.  It 
soon  finds  its  way  to  the  kidneys,  lungs,  and  skin,  to  be 
removed  from  the  body. 

Thus  the  bread  which  you  eat  and  take  into  the  body 
is  only  for  a  small  portion  of  the  time  really  a  living  part 
of  your  body. 

THOUGHT  QUESTIONS. — Tobacco.  1.  Chemical  analysis  shows 
that  there  is  enough  nicotin  in  one  cigar,  if  taken  into  th  i  circulation,  to 
kill  two  men.  Does  the  experience  of  tobacco  users  disprove  this? 
2.  What  means  have  shrewd  manufacturers  provided  so  that  even 
children  now  learn  to  smoke  so  gradually  as  not  to  awaken  the  instinc- 
tive repugnance  to  the  poison  in  tobacco?  '  3.  What  injury  results  from 
chewing  tobacco  that  does  not  result  from  smoking?  What  injury 
results  from  smoking  that  does  not  result  from  chewing?  Why  are 
weak  cigarettes  far  more  injurious  than  strong  cigars  ?  4.  Where  has 
the  smoke  been  that  a  boy  blows  out  of  his  nose?  5.  Give  two 
reasons  why  weak  tobacco  smoke  in  the  lungs  does  a  far  greater  amount 
of  injury  than  strong  tobacco  smoke  in  the  mouth.  6.  Why  do 
cigarette  smokers  usually  inhale,  or  draw,  the  smoke  into  the  lungs, 
while  cigar  smokers  do  not?  7.  Think  of  three  boys  (without  writing 
their  names)  whom  you  know  that  do  not  use  tobacco,  and  of  three  that 


152 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


smoke  cigarettes  habitually.  P'ill  out  the  following  table,  placing  trie 
boys  in  two  classes,  and  showing  how  many  of  the  three  tobacco  users 
are  fleshy,  and  how  many  are  thin,  etc. ;  how  many  of  the  three 
abstainers  are  fleshy,  how  many  of  the  three  are  thin,  etc. 


»i 

1 
E 

] 

i 

Pale  or 
Sallow 

•3 

1 

JU 

•3 

Obedient 

K 

I 

c 
P 

Bj 

p 
M 

3 
C/3 

3  tobacco  users 

_ 

3  abstainers 

Condiments  and  Narcotics.  —  Certain  substances  called 
condiments,  such  as  vinegar,  pepper,  and  mustard,  are 
sometimes  taken  for  the  purpose  of  exciting  a  dull  ap- 
petite. These  produce  a  slightly  increased  flow  of 
the  digestive  juices  and  much  mucus.  They  cannot  be 
classed  with  any  of  the  four  classes  of  nutritious  food. 
The  nerves  become  dulled  to  them  if  used  beyond  a  very 
moderate  amount.  When  appetite  is  lacking,  it  should 
not  be  stimulated,  lest  more  food  be  taken  than  the  cells 
can  assimilate.  Part  of  it  will  be  changed  into  injurious 
waste  material,  poison  the  tissues,  and  burden  the  organs 
of  excretion.  Alcohol,  opium,  and  tobacco  decrease  the 
feeling  of  hunger,  not  by  supplying  food,  but  by  benumbing 
the  nerves.  By  dulling  the  instinct  for  food,  they  may 
cause  the  body  to  be  insufficiently  nourished.  If  a  poor 
man  "breakfasts  off  a  pipe,"  his  body  is  still  as  much  in 
need  of  a  breakfast  as  it  would  have  been  if  he  had  not 
smoked. 

The  Teeth.  —  The  first  and  one  of  the  most  important 
steps  in  digestion  is  chewing.  The  teeth  cut  and  grind 
the  food.  They  fit  into  deep  sockets  in  the  jaws.  Get  a 


FOOD  AND  DIGESTION 


153 


tooth  from  a  dentist,  and  saw  or  break  it  into  halves.     To 

study  the  parts  of  a  tooth  more  carefully,  sketch  Figure 

121  on  the  blackboard  or  in   your   notebook  on  a  large 

scale.    The  main  body  of  the  tooth 

consists  of   bonelike   dentine,    or 

ivory.    Hard,  shining  enamel  pro- 

tects the  crown,  or  visible  portion, 

The  part  of  the  tooth  beneath  the 

gum  is  called  the  neck,  and  the 

part  in  the  bony  socket  is  called 

the  root.     The  enamel  ends  just 

beneath    the    gum,    where    it    is 

overlapped  by  cement  of  the  root. 

There  is  a  pulp  cavity  in  every 

tooth  (Fig.  121);  it  contains  pulp 

made  up  of  connective  tissue,  with 

nerves  and  blood  vessels  which 

enter  at  the  tip  of  the  root.    Since 

an  infant  cannot  eat  solid  food, 

it  needs  no  teeth  for  the  first  few 

months. 

At  about  the  age  of  six  months  the  first  teeth  of  the 

temporary  set  appear  ;  this  set  is  completed  at  about  two 

years  of  age  and  consists  of  twenty  teeth  (Fig.  122).    The 

teeth  cannot  grow 
as  the  jaw  grows, 
and  soon  a  larger 

Central  incisor  \J          \J  ~  and  permanent  set 

Lateral  incisor          Canine  1st  molar  starts  to  growing 

FIG.  I23.-THE  MILK  TEETH  in  one  half  of  one  jaw. 


AhreoUr  periosteum  or  root- 


FIG.  i2i.  — CANINE  TOOTH  cur 
LENGTHWISE. 


The  second  set  begins  to  push  out  the  first  set  at  about  five 
or  six  years  of  age.  At  the  age  of  twelve  or  thirteen  years 
all  the  permanent  set  have  appeared  except  the  four  wisdom 


154 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


teeth,  which  appear  between  the  ages  of  twenty  and 
twenty-five.  The  second  set  not  only  replace  the  twenty 
of  the  first  set,  but  to  supply  the  larger  jaws  twelve  molars 
are  added,  three  at  the  back  in  each  half  jaw,  making 
thirty-two  teeth  in  the  second  set.  The  teeth  in  each 
quarter  of  the  mouth,  named  in  order  from  the  front,  are 
as  follows:  two  incisors ;  one  canine,  two  bicuspids,  three 
molars  (Fig.  123). 


3rd  molar  1st  molar  1st  pre molar     •f       Lateral  mcisor 

2nd  molar  2nd  premolar  Caiime  Central  incisor 

FIG.  123.— THE  PERMANENT  TEETH  in  right  half  of  lower  jaw.   See  also  Fig.  163. 

Observation  of  the  Teeth.  —  Sit  with  the  back  to  the 
light  and  look  into  a  mirror,  with  the  mouth  wide  open. 
Do  you  see  the  four  kinds  of  teeth  named  above  ?  Which 
are  fitted  for  cutting?  Which  for  grinding?  Are  any 
suited  for  tearing  ?  Are  any  of  the  teeth  pointed  ?  What 
is  the  difference  in  the  bicuspids  and  molars  ?  Are  there 
any  decayed  places  ?  Are  the  teeth  clean  ?  Are  the  so- 
called  canine  teeth  so  long  that  they  project  beyond  the 
line  of  the  other  teeth  as  they  do  in  a  dog  ?  Do  the  edges 
of  the  upper  and  lower  incisors  meet  when  the  mouth 
is  closed,  or  do  they  miss  each  other  like  the  blades  of 
scissors  ?  How  many  roots  has  each  lower  tooth  ?  (See 
Fig.  123.)  Which  tooth  has  the  longest  root? 

Care  of  the  Teeth.  —  The  best  way  to  care  for  the  teeth 
is  to,  keep  the  digestion  perfect.  Perfect  digestion  tends  to 
preserve  the  teeth,  and  perfect  teeth  tend  to  keep  the 


FOOD  AND  DIGESTION  155 

digestion  perfect.  The  teeth  should  be  washed  regularly. 
A  toothpick  is  as  effective  as  a  toothbrush  in  keeping  the 
teeth  clean.  If  one  eats  only  soft  food,  in  which  the  mill 
and  the  cooking  stove  have  left  no  work  for  the  teeth,  the 
teeth  will  decay ;  for  it  seems  to  be  a  law  of  nature  that 
useless  organs  are  removed.  The  pressure  from  chewing 
hard  food  is  an  aid  to  the  teeth  by  helping  the  circulation 
and  nerves  in  the  pulp.  To  take  anything  very  hot  or  very 
cold  into  the  mouth  may  cause  the  enamel  to  crack.  If  a 
tooth  aches,  or  a  small  decayed  place  is  found  in  it,  a 
dentist  should  be  consulted  at  once.  A  tooth  is  so  valu- 
able to  the  health  that  no  tooth  should  be  extracted  when 
it  can  be  saved.  A  good  dentist  can  save  a  tooth  in  almost 
any  condition. 

The  process  of  digestion  consists  in  making  the  food 
soluble  that  it  may  pass  through  the  walls  of  the  food 
tube  into  the  blood,  and  through  the  walls  of  the  blood 
vessels  into  the  tissues.  It  is  accomplished:  (i)  by 
mecJianical  means,  including  the  chewing  muscles,  the 
teeth,  and  the  muscles  in  the  walls  of  the  food  tube ; 
(2)  by  chemical  means,  or  the  action  of  alkalies  and  acids 
upon  the  food ;  (3)  by  organic  agency,  or  the  action  of 
ferments.  A  ferment  (or  enzyme)  is  a  vegetable  substance 
which  has  the  power  of  producing  a  chemical  change  in 
large  quantities  of  substance  brought  in  contact  with  it, 
without  being  itself  changed.  There  is  one  ferment 
secreted  in  the  mouth,  two  in  the  stomach,  and  three  in 
the  small  intestine. 

Digestion  in  the  Mouth. —  Saliva  is  formed  by  six 
glands :  one  in  the  cheek  in  front  of  each  ear  (see  Fig. 
63),  one  at  the  angle  of  each  lower  jaw,  and  one  pair  is 
beneath  the  tongue.  Each  gland  opens  into  the  mouth  by 
a  duct.  Saliva  is  ropy  because  it  is  mixed  with  mucus 


S6 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


formed  by  the  mucous  membrane  lining  the  mouth  ;  it 
usually  contains  air  bubbles.  There  is  ferment  in  the 
saliva  called  ptyalin,  which  has  the  power  of  changing 
starch  to  malt  sugar.  If  a  bit  of  bread  is  chewed  for  a 
long  time,  it  becomes  sweet,  because  some  of  the  starch  is 
changed  to  sugar.  The  flow  of  saliva  is  caused  by  chewing, 
or  by  the  sight,  or  even  the  thought,  of  agreeable  food. 
Dryness  of  food  is  by  far  more  powerful  than  anything 
else  in  causing  the  saliva  to  flow.  Saliva  is  deposited 


FIG.  124.  — CELLS  OF  A  SALIVARY  GLAND. 

A,  after  rest,  full  of  granules;  B,  after  short  activity;  C,  after  prolonged  activity,  cells 
shriveled  and  granules  lost. 

only  one  fourth  as  fast  when  eating  oatmeal  and  milk  as 
when  eating  dry  toast.  Starchy  grains  and  fruits  were 
eaten  by  early  man  without  cooking,  and  required  more 
chewing  than  sweet,  ripe  fruits  or  oils  or  proteids.  Hence 
the  saliva  was  given  the  power  of  acting  upon  the  starch, 
for  they  must  remain  in  the  mouth  longer.  The  saliva  is 
alkaline ;  and  if  the  food  is  not  thoroughly  mixed  with  it, 
the  stomach  digestion  will  also  be  imperfect,  for  the  alka- 
line saliva  is  necessary  to  excite  the  flow  of  gastric  juice 
in  the  stomach  (Fig.  124). 

Saliva  moistens  dry  foods  which  cannot  be  swallowed, 
dissolves  food  that  it  may  be  tasted,  and  aids  in  the  move- 
ments of  the  tongue  in  speech.  Fear  prevents  its  secre- 
tion ;  and  the  Bible  tells  of  men  who  could  not  speak 
because  the  "tongue  clave  to  the  roof  of  the  mouth." 


FOOD  AND  DIGESTION1  157 

Chewing  gum  is  a  coarse  and  impolite  habit,  and  wastes 
the  saliva,  besides  weakening  the  glands  and  irritating 
the  stomach  by  the  saliva  that  is  continually  swallowed. 
Chewing  tobacco  has  several  of  these  disadvantages,  besides 
allowing  the  poison  in  the  tobacco  to  be  absorbed  by  the 
mucous  lining  of  the  mouth. 

The  pharynx  (far'inks),  or  throat,  is  a  muscular  bag 
suspended  behind  the  nose  and  mouth  (see  Fig.  91,  also 
Fig.  108).  There  are  seven  openings  into  the  pharynx: 
two  from  the  nostrils,  two  from  the  ears,  one  each  from  the 
mouth,  larynx,  and  gullet.  Which  of  these  openings  are 
downward  ? 

The  gullet  (or  esophagus)  is  a  muscular  tube  about  nine 
inches  long  (see  Fig.  108).  Like  the  rest  of  the  food  tube, 
it  is  lined  with  mucous  membrane.  It  has  two  layers  of 
muscles  in  its  walls,  the  fibers  of  one  layer  running  length- 
wise, and  the  fibers  of  the  other  layer  being  circular.  In 
swallowing  the  food  does  not  fall  down  the  gullet  of  its 
own  weight,  but  is  pressed  down  by  the  muscles  of  the 
gullet.  When  food  enters  the  pharynx,  the  muscular 
walls  of  the  pharynx  quickly  push  it  into  the  gullet. 
There  the  circular  bands  of  muscle  in  front  of  the  food 
relax,  and  those  behind  it  contract  and  push  it  on  into  the 
stomach.  This  action  is  plainly  seen  in  the  neck  of  a 
horse  when  he  is  drinking  water.  Both  food  and  water 
cannot  only  be  swallowed  down,  but  also  up,  as  in  vom- 
iting. The  gullet  is  always  closed  when  not  in  use.  See 
colored  Fig.  9 ;  also  Photomicrographs,  Fig.  73. 

Importance  of  Prolonged  Chewing.  —  Recent  experiments 
at  the  universities  of  Yale  and  Cambridge  (England)  serve 
to  show  that  prolonged  chewing  of  food  increases  greatly 
its  nutritive  poiver,  so  that  the  amount  of  food  eaten  may 
be  diminished  by  one  third  without  reducing  the  strength 


158 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


or  weight  of  the  body.  By  eating  very  slowly,  food  is  kept 
in  the  mouth  until  all  its  taste  is  extracted,  making  it  the 
most  enjoyable  way  of  eating.  People  who  eat  in  this  way 
are  found  to  have  remarkable  strength,  muscular  endurance, 
and  health,  and  to  have  an  increase  in  self-control  of  mind 

and  feelings.  They  are 
able  to  know  the  amount 
and  kind  of  food  that 
the  body  needs  ;  these  in- 
stincts are  lost  by  more 
hasty  eaters.  If  the  eater 
can  only  keep  his  hands 
lying  idly  on  the  table,  or 
in  his  lap,  for  a  good  part 
of  the  time,  it  is  easy  to 
eat  slowly.  If  he  puts 
food  into  his  mouth  rap- 
idly it  must  be  swallowed 
rapidly.  Invalids  have  re- 
gained health  by  learn- 
ing to  munch  their  food. 
Gladstone  said  jocularly, 
that  every  morsel  of  food 
should  be  given  thirty-two 

bites     that    every    tooth 
FIG.  125.  — THE  ALIMENTARY  CANAL          .   .       .  . 

except  mouth  and  gullet.  might  have  a  chance  at 

C,  stomach;   />,  pylorus;    AC,  ascending  colon;     jt.       Without    Ms    habit    of 
TC,  transverse  colon;    DC,  descending  colon; 

SF,  sigmoid  flexure;  R,  rectum.     The  excreta     thorough      chewing,      it     IS 
collect  in  the  sigmoid  flexure  and  descend  at 

intervals  into  the  rectum,  whence  they  are  re-     doubtflll  whether  he  WOUld 
moved  from  the  body. 

have  been  able  to  preserve 

his  remarkable  health  and  strength  to  so  great  an  extent  as 
to  have  been  called  "the  grand  old  man"  at  eighty  years 
of  age. 


FOOD  AND  DIGESTION1  1 59 

4 

The  stomach,  the  greatest  enlargement  of  the  food  tube, 
is  like  a  large  bag  lying  sideways.  It  lies  to  the  left 
side  of  the  abdomen  (see  colored  Fig.  9,  also  Fig»  125). 
The  walls  of  the  stomach  consist  chiefly  of  muscular  fibers 
which  run  lengthwise,  crosswise,  and  slantivise,  making 
three  coats.  As  soon  as  the  food  reaches  the  stomach, 
the  layers  of  muscles  begin  to  contract,  changing  the 
size  of  the  stomach,  first  in  length,  then  in  breadth, 
thus  churning  the  food  to  and  fro,  and  mixing  it  with 
the  gastric  juice,  a  fluid  more  active  than  the  saliva.  For 
as  soon  as  the  food  enters  the  stomach,  the  mucous  mem- 
brane lining  it  blushes  a  rosy  red,  and  many  little  gastric 
glands  (colored  Fig.  n)  in  the  lining  begin  to  secrete  gas- 
tric juice.  See  the  author's  Flat  Manikin,  Plates  III,  IV. 

Experiment  33.  Get  a  piece  of  tripe  from  the  market. 
Study  its  several  coats.  The  velvety  inner  coat  is  covered 
with  mucous  membrane.  See  photomicrograph,  Fig.  73. 

Digestion  in  the  Stomach.  —  The  stomach  churns  the 
food  from  two  to  four  hours  after  the  meal,  according  to 
the  kind  of  food  eaten,  the  way  it  has  been  cooked,  and 
the  thoroughness  with  which  it  has  been  chewed.  The 
gastric  juice  is  chiefly  water,  and  contains  two  ferments 
called  pepsin  and  rennin,  and  a  small  quantity  of  hydro- 
chloric acid.  Rennin  acts  upon  the  curd  of  milk,  and  is 
abundant  only  during  infancy.  Hydrochloric  acid  kills 
germs  that  may  enter  the  stomach,  and  changes  the  food 
which  has  been  made  alkaline  by  the  saliva  into  an  acid 
condition.  This  enables  the  pepsin  to  act  upon  the  proteid 
part  of  the  food,  for  pepsin  will  not  act  while  the  food  is 
alkaline.  Gastric  juice  digests  lean  meat,  which  is  a  pro- 
teid food,  by  first  dissolving  the  connective  tissue  that 
holds  the  fibers  in  place,  and  they  fall  apart ;  it  then  acts 
upon  the  fibers  separately  and  makes  them  soluble.  Like 


160 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


human  fatty  tissue  (Fig.  13),  fat  meat  consists  of  cells 
filled  with  fat  and  held  together  by  threads  of  connective 
tissue.  The  cell  walls  and  the  threads,  both  being  proteid, 
are  soon  dissolved  by  the  gastric  juice,  and  the  free  fat 
is  melted  into  oil,  but  still  undigested.  The  food  is  re- 
duced in  the  stomach  to  a  creamy,  half-fluid 
mass  called  chyme. 

The  Pylorus.  —  Where  the  stomach  opens 
into  the  small  intestine,  there  is  a  folding 
in  or  narrowing  of  the  tube  so  as  to  form  a 

of  kind  of  valve  called  the  pylorus  (see  Fig. 

FIG.  126.— PYLORUS. 


chyme,  this  fold  relaxes  every  minute  or  two,  and  allows 
some  of  the  chyme  to  escape  into  the  intestine ;  after 
several  hours  it  relaxes  altogether  and  allows,  not  only 
chyme,  but  any  parts  of  the  food  that  are  still  solid,  to 
pass.  Before  this,  anything  solid,  by 
touching  the  pylorus  would  only  have 
caused  it  to  close  more  tightly. 

The  small  intestine  is  about  one  inch 
in  diameter  and  twenty  feet  long,  with 
coils  arid  turns  in  its  course  (Fig.  125). 
Its  mucous  lining  is  wrinkled  into  numer- 
ous  folds  in  order  to  increase  the  secret- 
ing and  absorbing  surface  (Fig.  127), 
On  and  between  the  folds  are  thou- 
sands of  little  threadlike  projections 
called  villi  (Fig.  128).  In  each  villus 
are  found  fine  capillaries  and  a  small 
lymphatic  called  a  lacteal.  The  villi 
are  so  thick  that  they  make  the  lining 
of  the  intestine  like  velvet,  and  enormously  increase  the 
absorbing  surface. 


cut  open  to  show  the 

folds  in  its  lining. 


FOOD  AND  DIGESTION  l6l 

Digestion  in  the  Small  Intestine.  —  This  is  by  far  the 
most  active  and  important  of  the  digestive  organs.  The 
mouth  digests  a  small  part  of  the  starch,  and  the  stomach 
digests  a  small  part  of  the  proteid ;  the  small  intestine 
digests  most  of  the  starch,  most  of 
the  proteid,  and  all  of  the  fats.  The 
food  is  in  the  mouth  a  few  minutes, 
and  in  the  stomach  two  or  three  hours; 
it  is  in  the  small  intestine  ten  or 
twelve  hours.  There  are  thousands  of 


small  glands  called  intestinal  glands   FlG>    I28  _  LlNING    OF 
that  open  between  the  villi(Fig.  128)       SMALL  INTESTINE,  mag- 

nified,  showing  villi  and 

and  secrete  the  intestinal  juice,  which       mouths  of    intestinal 
digests  cane  sugar.      Besides  these, 
there  are  two  very  large  and  active  glands,  the  pancreas 
and  liver,  which  are  set  somewhat  apart  from  the  intestine 
and  empty  into  it  by  ducts. 

The  Pancreas.  —  The  small  intestine  is  the  most  impor- 
tant of   the  digestive  organs,  chiefly  because  it   receives 
the   secretion  from  the  pancreas,  the  most  important  of 
digestive  glands.     The   pancreas   is   a  long,  flat,  pinkish 
gland  situated  behind  the  stomach  (see  Fig.  120).      The 
'$$!&&£&         pancreatic  juice  contains  three  powerful 
^^;|;«ff^^>v    ferments,    one    of     which     digests     the 
j    starches,   another  digests   proteids,   and 
/     the  third,  with  the  aid  of  the  bile,  breaks 


ftfewaewr       up  the  fats  into  tiny  giobuies.      Fat  in 


FIG.  129.— A  DROP  OF  sma^  globules  floating  in  a  liquid  is  called 
CREAM,  showing  oil  an  emulsion ;   fresh  milk  is  an  emulsion 

globules. 

of  cream  (Fig.  129).  Fat  is  not  changed 
to  another  substance  by  digestion,  but  it  is  emulsified,  and 
in  this  condition  it  readily  passes  through  the  walls  of  the 
intestines  and  is  absorbed  by  the  lymphatics  called  lactealst 


1 62  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

found  in  the  villi.  It  then  ascends  through  the  thoracic 
duct  to  a  large  vein  at  the  left  side  of  the  neck  (see  colored 
Fig.  15).  The  digested  proteid,  starch,  and  sugar  pass  into 
the  capillaries  of  the  portal  vein,  and  go  to  the  liver  on  their 
way  to  the  general  circulation.  As  you  learned,  the  portal 
circulation  empties  into  the  large  ascending  vein  leading 
to  the  right  auricle. 

The  Liver.  —  This  large,  chocolate-colored  gland  is 
located  just  beneath  the  diaphragm  on  the  right  side  (Fig. 
120,  colored  Fig.  16).  It  is  on  a  level 
with  the  stomach,  which  it  partly  over- 
laps in  front.  The  liver  has  three  im- 
portant functions  :  ( i)  //  is  a  store  room; 
digested  sugar  and  starch  are  stored  in 
it  as  a  substance  called  liver  starch, 
or  gly'cogen  (Fig.  130).  (2)  It  is  a 
guardian,  and  destroys  poisonous  sub- 
stances which  may  be  swallowed,  and 
which  would  otherwise  enter  the  blood. 
Twice  as  much  poison  is  necessary  to 
FIG.  ISO.-LIVER  CELLS  ]^\\  a  man  when  it  is  given  by  the  mouth 

of  a  dog  after  36  hours' 

fast  (above) ;  also  14  and  passes  through  the  liver  as  when  it 
SSS  *  injected  through  the  skin.  Alcohol, 
ceils  swollen  with  liver  morphine,  coffee,  and  drugs  are  partly 

starch. 

burned  up  in  the  liver.  (3)  It  is  a 
gland,  and  secretes  bile.  The  bile  is  made  chiefly  from 
waste  products  and  impurities  in  the  blood  (see  colored 
Fig.  3)  >  it  is  an  excretion.  Although  an  excretion,  it  is 
of  great  use  on  its  way  out  of  the  body.  It  is  alkaline 
and  helps  to  neutralize  the  acid  in  the  chyme,  it  excites 
the  peristalsis,  or  wavelike  motion,  of  the  intestines,  and 
it  aids  the  pancreatic  juice  to  emulsify  the  fats.  See 
Figures  131  and  132. 


FOOD  AND  DIGESTION 


I63 


The  large  intestine,  or  colon,  is  about  two  and  one  half 
inches  in  diameter  and  five  feet  long.     The  small  intestine 


FIG.  131.  — VEINS  in  one  lobule  of 
liver.    See  colored  Fig.  3. 


FIG.  132.  — BILE  DUCTS  AND  LIVER 
CELLS  in  one  lobule.  (Cunningham.) 


joins  it  in  the  lower  right  side  of  the  abdomen  (Fig.  125). 
There  is  a  fold  or  valve  at  the  juncture,  and  just  below 
the  juncture  there  is  a 
tube  attached  to  the  large 
intestine,  called  the  ap- 
pendix, which  sometimes 
becomes  inflamed,  caus- 
ing a  disease  called  ap- 
pendicitis (Fig.  133). 
Absorption  of  the  watery 
part  of  the  food  continues 
in  the  colon,  but  the 
colon  secretes  no  diges- 
tive fluid.  The  undi- 
gested food  and  innutri- 
tious  parts  of  the  food 
are  regularly  cast  out  of  the  colon.  The  peritoneum  is  a 


VERMIFORM  APPENDIX 

FIG.   133.  —  JUNCTION  OF  LARGE  AND 
SMALL  INTESTINE. 


164 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


Diaphragm 


membrane  with  many  folds  that  supports  the  food  tube 
(Fig.  134). 

Experiment  34.  Make  a  model  of  the  food  tube  out 
of  cambric,  giving  to  each  organ  its  correct  size. 

Absorption. — The  way  in  which  the  various  digested 
foods  are  absorbed  has  been  stated  in  several  preceding 

topics.  What  is  the  name  of 
the  organs  of  absorption  in  the 
small  intestine  ?  Which  of  the 
following  pass  into  the  lacteals, 
and  which  into  the  capillaries : 
sugar,  digested  proteid,  emulsi- 
fied fats  ?  Water  and  salt  need 
no  digestion,  and  are  absorbed 
all  along  the  food  tube,  the 
absorption  beginning  even  in 
the  mouth.  What  reasons  can 
you  give  for  the  absorption  of 
food  being  many  times  greater 
in  the  small  intestine  than  in 
the  stomach  ?  Through  what 
important  vessel  is  the  fat  car- 
ried in  passing  from  the  lac- 
teals  to  the  veins  ?  Into  what 
large  vein  do  all  the  capillaries 
that  take  part  in  absorption  empty?  (p.  150.)  What  is 
the  provision  for  storing  the  sugar  so  that  it  will  not  pass 
suddenly  into  the  blood  after  a  meal,  but  may  be  given  to 
the  blood  gradually  ?  Trace  the  absorption  of  a  piece  of 
bread  as  given  in  a  previous  paragraph. 

THOUGHT  QUESTIONS. — The  Digestive  Organs.  1.  In  which  of 
the  digestive  organs  is  only  one  kind  of  secretion  furnished  from  glands  ? 
2.  In  which  organ  are  three  kinds  of  secretions  furnished  by  glands  ? 


FIG.  134.  — DIAGRAM  OF  TRUNK 
to  show  the  peritoneum  enfold- 
ing the  abdominal  organs.  Cut 
edge  of  the  peritoneum  appears 
as  a  white  line. 


FOOD  AND  DIGESTION  165 

3.  Which  class  of  food  goes  through  the  lymphatics  ?  4.  Which 
classes  of  foods  go  through  the  liver  ?  5.  Which  classes  of  foods  are 
digested  in  only  one  organ  ?  6.  Which  classes  of  foods  are  digested  in 
two  organs  ?  7.  Which  division  of  the  food  tube  is  longest ;  broadest ; 
least  active  ;  most  active  ?  8.  Soup  is  absorbed  quickly  ;  why  does  eat- 
ing it  at  the  beginning  of  a  meal  tend  to  prevent  overeating  ? 

Some  Differences  of  Opinion  about  Diet.  —  Some  persons 
believe  that  the  stomach  should  be  humored  and  given 
nothing  that  it  digests  with  difficulty ;  others  believe  that 
it  should  be  gradually  trained  to  digest  any  nutritious  food 
that  seems  to  disagree  with  it.  Some  believe  that  no 
animal  food  should  be  eaten  ;  others  believe  that  animal 
food  is  the  most  valuable  of  all.  Some  believe  that  all 
food  should  be  eaten  raw ;  others  believe  that  raw  food  is 
the  least  valuable  of  all.  Some  believe  that  no  form  of 
stimulant,  neither  tea  nor  coffee,  pepper  nor  alcohol,  should 
be  used ;  others  believe  that  they  are  beneficial  in  moder- 
ate amounts.  Some  eat  fast  and  drink  freely  at  meals ; 
others  eat  slowly  and  drink  very  little  or  none  at  all  while 
eating,  nor  for  an  hour  and  a  half  after  a  meal.  Some  eat 
five  meals  a  day  and  between  meals,  if  anything  that  tastes 
good  is  offered  them ;  others  eat  only  two  or  three  meals  a 
day,  and  never  between  meals,  thus  allowing  the  digestive 
organs  time  to  rest.  Some  omit  breakfast  and  some  omit 
supper.  Some  prepare  most  of  the  food  with  grease ; 
others  avoid  grease  almost  entirely.  Physical  workers 
often  believe  in  eating  the  peelings  and  seeds  of  fruits, 
and  partaking  freely  of  weedy  vegetables,  such  as  cabbage, 
turnip  tops,  string  beans ;  mental  workers  usually  try  to 
reject  all  woody  fiber  and  indigestible  pulp  from  the  food 
before  swallowing  it.  Some  eat  large  quantities  of  food  and 
digest  a  small  portion  ;  others  eat  little  but  digest  nearly  all. 

The  Power  of  Adaptation  of  the  Digestive  Organs.  —  Of 
course  some  of  these  ways  are  better  for  the  health  than 


1 66  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

others,  yet  the  undesirable  ways  often  bring  so  little  injury 
that  they  are  not  discontinued.  This  shows  that  the  food 
tube  has  great  powers  of  adaptation  to  different  conditions. 
But  there  are  limits  to  this  adaptation  ;  there  is  an  old  say- 
ing that  what  is  one  man's  meat  is  another  man's  poison. 
A  brain  worker  cannot  follow  the  same  diet  as  a  field  hand 
without  working  at  a  disadvantage.  An  irritable  stomach 
may  be  injured  by  coarse  food  that  would  furnish  only  a 
healthful  stimulus  to  a  less  sensitive  one.  A  business 
man  who  has  little  time  for  dinner  should  take  it  after 
business  hours.  In  general,  it  may  be  said  that  it  does 
not  make  so  much  difference  what  is  eaten  as  how  it  is 
eaten,  and  how  mtich  is  eaten. 

THOUGHT  QUESTIONS.  —  Indigestion.  I.  A  Fetid  Breath.  1. 
Name  three  causes  of  bad  breath.  2.  Let  us  investigate  whether 
indigestion  could  cause  a  bad  breath.  In  what  kind  (two  qualities) 
of  weather  does  meat  spoil  the  quickest?  3.  Suppose  that  meat  or 
other  food  is  put  into  a  stomach  with  its  gastric  glands  exhausted  and 
its  muscular  walls  tired  out,  what  will  be  the  rate  of  digestion,  and 
what  might  happen  to  the  food?  4.  Odorous  contents  of  the  stomach 
(e.g.  onion)  can  be  taken  by  the  blood  to  the  lungs. 

After  answering  the  above  questions,  write  in  a  few  words  how 
indigestion  may  cause  a  bad  breath. 

II.  A  Coated  or  Foul  Tongue.      1.  When  the  doctor  visits  you,  at 
what  does  he  first  look?      2.    What  sometimes  forms  on  old  bread? 
(p.  125.)       3.  Do   you  think  such  a  growth  possible  on  undigested 
bread  in  the  stomach  ?      4.  The  microscope  shows  the  coating  on  the 
bread  to  be  a  growth  of  mold.     If  it  forms  on  the  walls  of  the  stomach, 
it  may  extend  to  what? 

III.  Stomach  Ache.      1.  How  can  you  tell  whether  fruit  preserved  in 
a  sealed  glass  jar  is  fermenting?     2.  What  connection  is  there  between 
belching  at  times  after  eating  too  freely  of  sweet  or  starchy  food,  and 
the  observation  above  ?      3.  A  muscle  gives  pain  when  it  is  stretched- 
Why  does   belching   sometimes   give   relief  to  an   uneasy  stomach? 
4.  Can  you,  by  using  these  facts,  explain  a  cause  of  stomach  ache? 

For  what  Kind  of  Man  were  the  Human  Digestive  Organs 
Created?  —  That  food  is  best  to  which  the  food  tube  has 


FOOD  AND  DIGESTION  167 

been  longest  accustomed.  It  would  be  of  the  greatest 
value  as  a  guide  to  diet  if  we  knew  the  kind  eaten  by  early 
man  during  the  many  ages  when  he  led  a  wild  life  in  the 
open  air.  The  organs  of  early  man  were  doubtless  per- 
fectly adapted  to  the  life  he  led.  The  food  tube  is 
adapted  to  the  needs  of  those  long  ages ;  for  a  few  cen- 
turies of  civilization  cannot  change  the  nature  of  the 
digestive  organs:  yet  some  people  disregard  natural 
appetites  and  try  to  force  the  digestive  organs  to  undergo 
greater  changes  in  a  few  months  than  centuries  could 
bring  about. 

To  test  whether  an  Article  of  Food  belonged  to  Man's 
Original  Diet.  —  Scientists  agree  that  the  human  race  be- 
gan in  a  warm  country ;  that  early  man  was  without  grist- 
mills, stoves,  or  fire,  and  ate  his  food  raw.  If  an  article  of 
food  is  pleasant  to  the  taste  in  its  raw,  unprepared  state, 
there  is  little  doubt  that  it  or  a  similar  food  was  eaten  by 
primitive  man  before  he  knew  the  use  of  fire  in  preparing 
his  food.  Apply  this  test  to  the  following  foods,  under- 
lining those  foods  that  fail  to  pass  the  test :  apples, 
bananas,  lettuce,  turnip  greens,  turnips,  fruits,  nuts,  beef, 
butter,  fowls,  eggs,  oysters,  green  corn,  cabbage,  pork, 
watermelons,  grains,  crabs,  fish,  yams,  tomatoes. 

The  Order  in  which  Man  increased  his  Bill  of  Fare. — 
Flesh-eating  animals  have  a  short  food  tube,  as  their  food 
is  digested  quickly ;  they  have  long,  pointed  teeth  for  tear- 
ing, sharp  claws  for  holding,  and  a  rough  tongue  for  rasp- 
ing meat  from  the  bones.  Man's  even  teeth,  long  food 
tube,  soft  and  smooth  tongue,  and  flattened  nails  indicate 
that  he  is  suited  for  a  diet  largely  vegetable.  The  race 
at  first  probably  ate  tree  fruits?  both  nuts  and  fleshy  fruits. 
Because  of  famine,  or  after  migration  to  colder  climates, 

1  See  Genesis  i.  29. 


i68 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


Beef 


Bread 


Bananas 


Nuts 


Potatoes 


Lettuce 


and  after  learning  the  use  of  fire,  the 
race  probably  began  to  use  flesh  for 
food.  Afterward  the  hunters  became 
farmers  and  learned  to  cultivate  grain, 
which  formed  a  most  important  addi- 
tion to  the  food  supply,  and  made 
possible  a  thick  population.  Coarse, 
woody  foods,  like  the  leaves  and  stems 
of  herbs,  were  probably  added  last  of 
all.  Woody  fiber  (cellulose)  can  be 
digested  by  cattle,  but  it  cannot  be 
digested  by  man. 

Fruits  have  the  most  agreeable  of  all 
flavors.  They  contain  acids  that  kill 
germs  and  keep  the  food  tube  pure ; 
they  furnish  valuable  mineral  salts  that 
are  needed  by  the  tissues ;  they  contain 
sugar  in  its  most  digestible  form  (fruit 
sugar).  Since  fruit  juices  kill  germs, 
a  fruit  diet  for  a  day  will  often  purify 
the  food  tube,  relieve  constipation,  and 
ward  off  a  threatened  "bilious  "  attack. 
Fruit  is  pleasanter  medicine  than  drugs 
and  costs  less.  Green  fruit  or  decayed 
fruit  will  cause  illness  instead  of  curing 
it.  Fruit  contains  a  large  amount  of 
water.  Apples.  —  Baked  sweet  apples 
are  the  most  digestible  of  fruits.  Ripe 
sweet  apples  also  digest  very  quickly. 
Several  apples  eaten  a  half  hour  before 
breakfast  every  morning  are  more  ef- 
fective medicine  than  pills,  and  do  not 
derange  the  system.  The  banana  is, 


FOOD  AND  DIGESTION  169 

next  to  dried  figs,  raisins,  and  dates,  the  most  nourishing 
of  all  fruits.  A  pound  of  bananas  contains  as  much 
nourishment  as  a  pound  of  beefsteak  (see  Table,  p.  147). 
Green  bananas  taste  very  good  when  baked.  Bananas 
are  not  allowed  to  ripen  on  the  plant  even  for  use  in 
tropical  countries ;  most  fruit  is  better  when  so  ripened. 
A  banana  is  usually  not  thoroughly  ripe  until  its  skin  is 
partly  blackened.  Bananas  that  show  angles  were  pulled 
before  being  full  grown,  and  are  not  digestible  raw. 
Peaches  are  very  wholesome  and  delicious.  Since  their 
season  is  short,  a  good  supply  should  be  provided  by  pre- 
serving them  in  cans  or  glass  jars.  Cherries  are  more 
nutritious  than  apples  or  peaches.  Their  flesh  is  firm, 
and  they  should  be  thoroughly  chewed.  Pineapples ', 
when  allowed  to  mature  upon  the  plant,  are  a  luscious 
fruit ;  those  shipped  to  this  country  are  pulled  green  and 
are  indigestible  if  eaten  raw.  Strawberries  contain  much 
iron.  To  a  few  people  they  are  not  digestible.  Grapes 
are,  next  to  bananas,  the  most  nutritious  of  fresh  fruits 
(see  Table).  Their  effect  on  the  digestive  organs  is  so 
beneficial  that  sometimes  dyspeptics  try  the  grape  cure, 
and  confine  the  diet  entirely  to  grapes  for  several  weeks. 
Watermelons  are  a  source  of  the  purest  water  and  a  small 
amount  of  sugar.  The  pulp  is  of  tough  woody  fiber,  and 
if  it  is  removed  from  the  mouth  after  the  juice  has  been 
extracted,  and  it  has  become  a  tasteless  mass,  there  is  no 
danger  of  eating  too  much  watermelon.  If  the  pulp  is 
swallowed,  too  much  may  readily  be  eaten.  Lemons  fur- 
nish a  pleasant  and  healthful  drink. 

Nuts  contain  less  water  than  other  foods,  hence  they 
are  the  most  highly  concentrated  and  nutritious  of  all  foods 
(Fig.  135).  In  the  early  days  of  the  race  they  were  prob- 
ably the  chief  dependence  of  man.  The  oil  of  nuts  is  in  a 


I/O  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

state  of  emulsion,  or  cream,  and  is  much  more  digestible 
than  fat  meat.  Since  the  starch  of  green  nuts  is  changed 
to  sugar  in  the  ripe  nut,  the  proteid  is  the  only  part  of  the 
nut  that  requires  real  digestion.  The  prejudice  against 
nuts  among  persons  who  do  not  eat  properly,  or  who  are 
ignorant  of  food  values,  is  due  to  two  causes.  First,  nuts 
are  eaten  after  the  stomach  is  full,  or  they  are  eaten 
between  meals ;  second,  they  are  practically  indigestible 
when  hastily  chewed  and  swallowed  in  small  bits.  Nuts 
should  be  chewed  so  thoroughly  that  they  are  reduced  to  a 
creamy  pulp  before  they  are  swallowed.  The  pecan  con- 
tains twice  as  much  fat  as  ham  (see  Table) ;  it  is  the  most 
digestible  of  all  nuts ;  its  kernel  has  no  paperlike  skin 
over  it,  like  the  kernel  of  the  almond,  hickory  nut,  etc. 
Because  of  the  oil  in  pecans  they  cure  and  prevent  consti- 
pation. A  pound  of  almonds  contains  more  proteid  than  a 
pound  of  beefsteak,  besides  two  thirds  as  much  fat  as  a 
pound  of  butter  (see  Table).  Which  most  resembles  nuts 
in  composition,  beans,  peas,  or  peanuts  ?  Which  nut  has  a 
composition  most  like  that  of  grains  ?  (See  Table.)  Chest- 
nuts contain  little  fat  and  a  very  large  percentage  of 
starch.  They  are  used  for  bread  in  Italy,  where  they 
are  ground  into  meal  and  made  into  cakes.  The  cocoanut 
furnishes  almost  the  entire  diet  in  some  of  the  Pacific 
islands. 

Animal  Food.  —  The  flesh  of  animals  furnishes  proteid 
and  fat  (Fig.  136).  As  cooking  coagulates  and  hardens 
albumin,  raw  or  half-cooked  meat  is  said  to  be  more  diges- 
tible than  cooked  meat ;  but  meat  that  is  not  thoroughly 
cooked  is  dangerous  because  it  may  contain  the  trichina 
worm  and  other  parasites.  There  is  more  proteid  in  meat 
than  in  most  vegetable  foods,  and  it  is  more  completely 
absorbed  from  the  food  tube.  Some  persons  who  cannot 


FOOD  AND  DIGESTION 


171 


easily  digest  starch  and  sugar  because  of  fermentation  eat 
fat  for  a  fuel  food.  Beef  tea  and  beef  extracts  contain  but 
a  small  part  of  the  proteid  in  meat  and  all  of  the  waste 
matter,  including  urea.  Milk  of  cows  is  improperly  called 
a  perfect  food  by  some  writers.  Although  it  contains  the 


1.  sirloin 

2.  loin 

3.  rump 

4.  round 

5.  top  sirloin 

6.  prime  ribs 

7.  blade 

8.  chuck 

9.  neck 

10.  brisket 

11.  cross-rib 

12.  plate 

13.  navel 

14.  flank 

15.  shoulder 

16.  leg 


FIG.  136.  — DIAGRAM  SHOWING  CUTS  OF  BEEF. 


four  classes  of  food  stuffs,  the  proteid  is  in  excess,  the  fuel 
food  being  deficient.  Water  and  sugar  must  be  added 
when  it  is  fed  to  infants.  The  first  step  in  digesting 
milk  is  the  forming  of  many  small  curds ;  hence  curds 
thrown  up  by  an  infant  do  not  show  indigestion,  though 
it  may  show  that  its  stomach  is  too  full.  Milk  was  in- 
tended to  be  sucked,  not  to  be  drunk  in  gulps.  If  adults 
do  not  drink  sweet  milk  by  slowly  sipping,  it  is  likely  to 
form  large  indigestible  curds  causing  "biliousness"  and 
constipation.  Sour  milk,  or  "  clabber,"  and  curds  pressed 
into  "cottage  cheese"  are  more  digestible  than  sweet 
milk.  Cream  is  more  easily  digested  than  butter,  which 
is  a  solid  fat.  It  hardly  seems  logical  to  spend  a  long 
time  churning  milk,  which  is  an  emulsion,  in  order  to 
cause  the  particles  of  cream  to  adhere  into  a  solid  fat, 
and  then  to  eat  the  butter  and  let  the  food  tube  spend 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 

several  hours  reducing  it  to  an  emulsion  again.  It  is 
necessary  to  churn  cream  into  butter  for  convenience  in 
shipping,  and  because  it  keeps  fresh  longer ;  but  for  those 
who  can  obtain  fresh  cream,  it  may  well  be  eaten  instead 
of  butter,  being  used  as  "  whipped  cream  "  and  in  other 
ways.  Cheese  is  a  very  concentrated  proteid  food,  and 
should  be  eaten  sparingly.  Eggs  are  a  very  valuable  food. 
What  part  of  the  egg  contains  proteid  ?  Is  there  more 
proteid  or  fat  in  eggs  ?  (See  Table.)  Pork  and  veal  are  the 
most  indigestible  of  meats.  Fish  is  not  so  nutritious  nor 
so  easily  digested  as  meat.  There  used  to  be  a  supposi- 
tion that  fish  nourished  the  brain  because  it  contains 
phosphates ;  but  there  are  more  phosphates  in  meat  than 
in  fish,  and  more  in  grains  than  in  meat. 

Grains  contain  considerable  proteid  (gluten),  but  they 
especially  abound  in  starch.  Wheat  flour  contains  more 
gluten  than  corn  meal,  hence  it  is  more  sticky  and  retains 
the  bubbles  of  gas  so  that  the  dough  rises  well  in  bread 
making.  Eggs  are  sometimes  added  to  corn  meal  to  make 
it  sticky  and  cause  it  to  rise  well.  Which  grain  has  the 
largest  percentage  of  oil  ?  Of  starch  ?  Of  gluten  ?  Which 
is  poorest  in  gluten  ?  Grains  may  be  made  to  resemble  fruit 
by  long  cooking  at  a  high  temperature  (300°  Fahr.),  for 
their  starch  is  thus  changed  to  dextrin,  a  substance  resem- 
bling sugar.  You  learned  that  the  starch  of  fruit  is  turned 
into  sugar  as  the  sun  ripens  it.  Dextrin  is  yellow  and  gives 
the  dark  color  to  toasted  bread.  It  is  changed  to  sugar 
almost  instantly  when  brought  in  contact  with  saliva.  It 
is  used  as  a  paste  on  postage  stamps. 

Vegetables  include  the  stems,  roots,  and  leaves  of  plants. 
With  the  exception  of  beans,  peas,  and  potatoes,  vegetables 
are  the  least  nutritious  class  of  food ;  for  example,  onions, 
celery,  lettuce,  turnips,  carrots,  green  salads  (Fig.  137). 


FOOD  AND  DIGESTION 


173 


Cabbage  contains  a  small  amount  of  starch  (see  Table),  but 
it  is  slowly  digested  and  this  small  nourishment  hardly 
atones  for  its  exhausting  effect  upon  the  organs.  The  sul- 
phur in  it  gives  it  an  odor  which  can  be  detected  upon 
the  breath  until  it  leaves  the  stomach ;  often  this  is 


Prote/ct 
Ash 


Cabbage. 


JSA 


Starc/tfat 


Potato.  Carrot. 

FIG.  137.  —  SHOWING  COMPOSITION  OF  POTATO,  CABBAGE,  AND  CARROT.  (Jegi.) 

many  hours  after  it  has  been  eaten.  Vegetables  are  com- 
posed chiefly  of  water  and  woody  fiber.  Irish  potatoes 
are  underground  stems  and  are  one  fifth  starch.  Yams, 
or  sweet  potatoes,  resemble  roots,  and  contain  both  starch 
and  sugar.  Beans  and  peas  are  very  nutritious.  They 
have  been  called  "the  lean  meat  of  the  vegetable  king- 
dom." They  require  boiling  for  several  hours.  If  the 
skins  are  removed  by  pressing  them  through  a  colander, 
they  are  very  easy  of  digestion.  "Hull-less  beans"  are 
also  sold  by  grocers. 

PRACTICAL  QUESTIONS. — 1.  Clothing  and  shelter  for  man  or 
beast  economize  what  kind  of  food?  2.  Why  should  bread  remain 
longer  in  the  mouth  than  meat?  3.  In  snowballing,  what  is  the  appear- 
ance of  the  hands  when  they  itch  from  cold  ?  Extreme  cold  irritates 


174 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


PROTEfN 


FATS       CARBOHYDRATES     FUEL  VALUE' 


WEIGHTS  OF  NUTRIENTS  AND  CALORIES  OF  ENERGY 
IN  25  CENTS'  WORTH. 


CAL. 


»  VOIT  f  ATWATER 

FIG.  138.  —  NUTRIMENT  IN  TWENTY-FIVE  CENTS'  WORTH  OF  VARIOUS  FOODS. 

Which  food  in  the  table  is  the  dearest;  the  cheapest  ?  What  are  the  three  dearest;  the  three 
cheapest  ?  Which  food  furnishes  the  most  proteid  for  twenty -five  cents;  the  most  fat; 
carbohydrates  (sugar  and  starch)  ?  Compare  cost  of  animal  and  vegetable  foods. 


FOOD  AND  DIGESTION  175 

and  congests  the  stomach  more  quickly  than  it  does  the  hands.  Why 
is  it  that  ice  water  does  not  satisfy  the  thirst,  but  often  produces  a 
craving  to  drink  more  water?  4.  Should  biscuits  having  a  yellow  tint 
or  dark  spots  due  to  soda  be  eaten  or  thrown  away?  5.  Why,  during 
an  epidemic,  are  those  who  have  used  alcohol  as  a  beverage  usually  the 
first  to  be  attacked?  6.  Do  you  buy  more  wood  (cellulose)  when  you 
buy  beans  or  when  you  buy  nuts?  (p.  147.)  7.  Do  you  buy  more 
water  when  you  buy  bread  or  when  you  buy  meat?  8.  Why  do  people 
who  live  in  overheated  rooms  often  have  poor  appetites?  (p.  138.) 
9.  Explain  how  the  stomach  may  be  weakened  by  the  eating  of  predi- 
gested  foods.  10.  Why  is  deep  breathing  and  exercises  that  strengthen 
weak  abdominal  walls  better  for  the  liver  than  are  drugs?  (See  p.  87.) 
11.  Sixty  students  at  the  University  of  Missouri  found  by  doing  with- 
out supper  that  their  power  to  work  was  greater,  their  health  better, 
and  many  of  them  gained  in  weight.  So  they  only  ate  two  meals 
thereafter.  If  sixty  plowboys  tried  the  experiment,  would  the  result 
probably  have  been  the  same?  12.  If  a  person  began  to  eat  less  at 
each  meal,  or  only  ate  one  meal  a  day,  yet  gained  in  weight,  should  he 
agree  with  a  friend  who  told  him  he  was  starving  himself?  Should  he 
agree  if,  instead  of  gaining,  he  lost  weight?  13.  Why  is  half-raw  or 
soggy  bread  harder  to  digest  than  the  raw  grain  itself  ?  WThich  would 
be  thoroughly  chewed  and  cause  a  great  flow  of  saliva? 

Professor  At  water's  Experiments.  —  A  few  years  ago 
Professor  Atwater  proved  that  if  alcohol  is  taken  in  small 
quantities,  it  is  so  completely  burned  in  the  body  that  not 
over  two  per  cent  is  excreted.  He  inferred  that  it  is  a 
food  since  it  gives  heat  to  the  body  and  possibly  gives 
energy  also.  Dr.  Goddard  has  since  made  experiments  on 
dogs  and  found  that  seventy-five  per  cent  of  it  was  oxidized 
in  the  body  if  only  moderate  doses  were  given ;  if  large 
doses  were  given,  fifty  per  cent  was  excreted  unchanged. 

What  Professor  At  water's  Experiments  failed  to  Show.  — 
His  experiments  were  tried  on  persons  who  were  accus- 
tomed to  using  alcohol.  They  failed  to  show  what  the 
effect  would  be  on  human  beings  with  perfectly  natural 
bodies  unaccustomed  to  defending  themselves  against 
alcohol ;  the  experiments  also  failed  to  show  whether  in 


176  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

burning  up  the  alcohol  any  organ  was  weakened  or  injured 
thereby.  As  alcohol  is  chiefly  burned  in  the  liver,  it  prob- 
ably cannot  supply  energy  as  is  the  case  with  food  burned 
in  nerve  cell  and  muscle  cell.  Even  the  heat  supplied  by 
its  burning  is  chiefly  lost  by  the  rush  of  blood  to  the  skin 
usually  caused  by  drinking  the  alcohol. 

Dr.  Beebe's  Experiments  have  supplied  Some  of  the  Miss- 
ing Knowledge.  —  Dr.  Beebe,  unlike  Professor  Atwater, 
experimented  upon  persons  who  had  never  taken  alcohol, 
and  whose  bodies  had  not  had  time  to  become  trained  to 
resist  its  evil  effects.  He  found  that  owing  to  what  Neu- 
mann calls  its  action  as  a  protoplasmic  poison,  it  caused 
an  increased  excretion  of  nitrogen.  When  the  body  be- 
came used  to  it  this  decreased,  but  the  proteid  excreted  by 
the  kidneys  contained  an  abnormal  amount  of  a  poisonous 
material  called  uric  acid.  Now  uric  acid,  a  substance 
which  causes  rheumatism  and  other  diseases,  is  usually 
destroyed  by  the  liver.  As  the  burden  of  destroying  the 
alcohol  falls  chiefly  upon  the  liver,  it  is  not  surprising  to  find 
that  it  is  so  weakened  and  injured  by  alcoholic  drink  that 
it  cannot  perform  fully  its  important  function  of  destroy- 
ing uric  acid.  It  is  also  plain  why  rheumatism,  Bright's 
disease,  and  other  diseases  accompanied  by  uric  acid  are 
so  frequent  among  persons  who  use  alcoholic  drinks. 

Definition  of  Food.  —  A  food  is  anything  which,  after  being 
absorbed  by  the  body,  nourishes  the  body  without  injuring  it. 
Alcohol  does  not  come  within  this  definition. 

Advantages  of  Good  Cooking.  —  Taste  and  flavor  may  be 
developed  ;  parasites  are  killed ;  taste  may  be  improved  by 
combining  foods  ;  starch  grains  are  burst  and  the  food 
softened.  Food  well  cooked  is  already  partly  digested. 

Disadvantages  of  Bad  Cooking  —  Proteid  foods  are  hard- 
ened ;  flavors  may  be  driven  off ;  too  many  kinds  of  food 


FOOD  AND  DIGESTION  177 

may  be  mixed ;  cooked  vegetables  are  more  likely  to  fer- 
ment than  raw  vegetables ;  palatable  food  may  be  made 
tasteless  or  soggy  or  greasy ;  soda  and  other  indigestible 
ingredients  may  be  added  ;  food  may  be  so  highly  seasoned 
as  to  cause  catarrh  of  the  stomach ;  it  may  so  stimulate 
the  appetite  that  so  much  is  eaten  as  to  overload  the  stom- 
ach. Food  may  be  made  so  soft  that  it  cannot  be  chewed, 
and  is  eaten  too  rapidly ;  for  instance,  bread  shortened 
with  much  grease. 

The  Five  Modes  of  Cooking.  —  Food  may  be  cooked 
( i )  by  heat  radiating  from  glowing  coals  or  hot  metal  or 
a  flame ;  (2)  by  hot  airt  as  in  a  hot  oven  ;  (3)  by  boiling  in 
hot  water  or  grease ;  (4)  by  hot  water,  not  boiling,  as  in 
stewing  ;  (5)  by  steaming. 

Radiant  Heat  —  Toasting  bread  and  broiling  meat  are 
examples.  The  meat  should  be  turned  over  every  ten 
seconds  to  send  its  juices  back  and  forth,  thus  preventing 
their  escape,  and  broiling  the  meat  in  the  heat  of  its  own 
juices.  Roasting  is  an  example  of  this  method  combined 
with  the  second  method.  The  fire  should  be  hot  at  first 
in  order  to  sear  the  outside  of  the  meat  and  prevent  the 
escape  of  its  juices.  If  the  piece  roasted  is  small,  the  hot 
fire  may  be  kept  up ;  but  if  it  is  large,  a  longer  time  is 
required,  and  the  fire  should  be  decreased,  otherwise  the 
outside  will  be  scorched  before  the  central  part  becomes 
heated.  Irish  potatoes,  roasted  with  their  skins  on,  retain 
their  flavor  better  than  by  most  methods  of  cooking  them. 

Cooking  by  hot  air  can  only  be  used  with  moist  foods. 
Baking  is  an  example.  Foods  only  slightly  moist  are  made 
hard,  dry,  and  unpalatable  if  cooked  by  this  method. 

Cooking  by  Boiling.  —  To  boil  Irish  potatoes  and  make 
them  mealy  instead  of  soggy,  the  water  should  be  boiling 
when  they 'are  put  in,  and  after  they  are  cooked  the  water 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 

should  be  poured  off  and  the  pot  set  on  the  back  of  the 
stove  for  the  potatoes  to  dry  (Figs.  139,  140).  Boiling 
onions  drives  off  the  acrid,  irritating  oil.  Raw  cabbage  is 
treated  by  the  stomach  as  a  foreign 
substance,  and  sent  promptly  to  the 
intestine ;  cabbage  boiled  with  fat 
remains  in  the  stomach  for  five 
hours.  Instead,  it  should  be  boiled 
in  clear  water  for  twenty  minutes. 
Beans  and  fleas  require  long  boiling. 
FIG.  i39. -CELLS  OF  RAW  Cooking  in  hot  liquid  below  the 

POTATO  with  starch  grains 

inclosed  in  the  cellulose  boiling  point  is  better  than  boiling. 
In  frying  meat,  it  should  be  put  in 
hot  grease  that  a  crust  may  be  formed 
to  prevent  the  grease  from  soaking 
in.  Overheated  grease  becomes 
decomposed  into  fatty  acids  and 
other  indigestible  products.  In  what- 
ever way  meat  is  cooked,  it  should 
never  be  salted  until  it  is  cooked, 
FIG.  140.— CELLS  OF  POTATO  or  the  salt  will  draw  out  the  juices 

well  steamed  and  mashed.  .   . 

Starch  grains  have  been  which  flavor  it.    Eggs  may  be  cooked 

burst  by  the  heat  ^  pladng  them  jn  boiling  water  and 

setting  the  kettle  off  the  stove  at  once  to  cool.  Since 
boiling  for  more  than  a  very  few  minutes  coagulates  and 
hardens  albumin,  there  is  no  such  thing  as  boiling  meat 
without  making  it  tough  and  leathery  throughout.  It  may 
be  stewed,  a  process  which  belongs  to  the  next  method. 

In  stewing  meat,  it  may  be  plunged  into  boiling  water 
for  a  few  minutes  ;  this  coagulates  the  albumin  on  the 
surface.  The  fire  should  then  be  reduced,  or  the  vessel 
set  on  the  cooler  part  of  the  stove,  or  a  metal  plate  should 
be  placed  beneath  it,  that  the  water  may  barely  simmer. 


FOOD  AND  DIGESTION  179 

The  water  should  show  a  temperature  of  185°  or  190° 
if  tested  with  a  thermometer.  A  piece  of  meat  cooked 
in  this  way  is  tender  and  juicy  throughout. 

Cooking  by  steam  requires  a  double  vessel  or  a  vessel 
with  a  perforated  second  bottom  above  the  water,  through 
which  the  steam  may  rise  to  the  food  that  is  to  be  steamed. 
Steamed  vegetables  have  a  better  flavor  than  those  cooked 
in  any  other  way.  Oatmeal  should  be  cooked  for  at  least 
forty  minutes,  and  it  is  more  digestible  if  steamed  for 
several  hours  until  it  is  a  jelly.  To  do  this,  it  may  be 
cooked  during  the  preparation  of  two  meals.  Cooking 
that  leaves  it  lumpy  and  sticky  is  a  disadvantage,  and 
makes  it  more  likely  to  ferment  than  if  eaten  raw. 

THOUGHT  QUESTIONS.  —  Cooking.  Meat.  1.  In  making  soup,  why 
should  the  meat  be  put  in  while  the  water  is  cold  ?  2.  In  roasting 
meat,  why  should  the  oven  be  hot  at  first,  and  more  moderate  after- 
ward ?  How  should  you  regulate  the  temperature  in  boiling  or  stew- 
ing meat  ?  3.  What  happens  to  salt  or  anything  salty  on  a  cloudy, 

damp  day  ?  This  is  because  the  salt,  attracts  .  This  shows 

that  meat  should  not  be  salted  until  after  it  has  been  cooked,  because  if 

salted  before,  the  salt  will the  juices.  4.  Very  tough  meat  should 

be  b — ed  or  st — ed.  5.  Meat  is  allowed  to  become  grease-soaked 

when  it  is by cooks.  This  may  be  prevented  by  having  the 

grease  very ,  use  very ,  simply  greasing  the . 

6.  Bread.  Bread  crust  causes  the to  be  used  more  and  cleans 

them.  It  will  not together  in  the  stomach  like  the  crumb.  It  in- 
creases the  quantity  of  the ,  and  is  more  digestible  than  the  crumb, 

since  the  has  been  changed  by  slow  heat  to  .  (p.  172.) 

Therefore  loaves  or  biscuit  should  be  [large  or  small  ?]  and  they  should 
[touch  or  be  separated  ?]  in  a  pan.  7.  How  can  you  tell  whether 
the  oven  has  been  too  hot  while  the  bread  was  baking  ?  8.  Why  can 
you  tell  best  about  the  digestibility  of  bread  when  you  are  slicing  it  ? 
9.  Regulating  the  heat  is  the  greatest  art  of  the  cook.  How  may  the 
temperature  of  the  oven  be  lowered  by  means  of  the  damper?  The 
draft?  The  fuel? 

EXERCISES  IN  WRITING.  —  Story  of  a  Savage  who  went  to  dwell  in 
a  City  (his  trouble  with  artificial  ways).  Is  it  easier  to  learn  Physi- 
ology or  to  practice  it?  How  to  make  Bread.  Describe  People  seen 


180  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

in  an  Audience  (tell  what  their  appearance  suggests).  A  Scene  at  a 
Dinner  Table.  Thoughts  of  a  Physician  on  his  Round  of  Visits.  Prej- 
udices concerning  Food.  A  Good  Cook.  A  Bad  Cook.  Is  Cooking 
a  Greater  Accomplishment  than  Piano  Playing?  Common  Causes  of 
Illness.  The  Home  of  a  Reformed  Drunkard.  Alcohol  and  Duty  to 
Parents.  A  One-armed  Man  (loss  of  arm  due  to  drink).  The  Influence 
of  Imperfect  Digestion  upon  the  Other  Organs.  What  the  Blood  does 
for  the  Body.  Effect  of  Lack  of  Muscular  Activity.  The  Way  of  the 
Transgressor  is  Hard.  What  Fools  we  Mortals  be!  Health  Fads. 
Temperance  in  all  Things.  The  Right  Way  the  Easiest.  Looking 
Back.  Looking  Forward.  Hygiene  of  the  Schoolroom.  Patent  Medi- 
cines. Microbes.  Mind  Cure.  Nervous  Women.  Dissipated  Men. 
How  a  Friend  of  mine  lost  his  Health.  Why  a  Friend  of  mine  is  Sound 
and  Strong.  Useful  Labor.  Tobacco.  It  never  pays  to  neglect  the 
Health.  Which  does  more  Harm,  an  Ignorant  Cook,  or  an  Ignorant 
Janitor?  A  Visit  to  a  Sick  Room.  Why  I  believe  in  Games.  Write 
a  Letter  to  a  Friend  upon  meeting  a  Mutual  Schoolmate  who  took  to 
Drink.  Alcohol  and  Crime.  Natural  Instincts  and  Appetites:  how 
preserved,  how  lost.  A  Lesson  about  Alcohol  based  upon  the  Morning 
News.  Effects  of  Alcohol  upon  the  Greatness  of  our  Country  (work- 
men, voters,  soldiers,  children). 

Physicians  and  Alcohol.  —  Three  times  during  the  last  century 
medical  manifestoes  were  issued  giving  the  opinion  of  physicians  on 
alcohol.  The  first  was  issued  in  1839,  and  was  signed  by  eighty-six 
persons.  The  second  was  in  1847,  and  was  signed  by  two  thousand 
physicians,  and  the  third  appeared  in  1871,  with  the  signatures  of  over 
four  thousand  physicians,  including  the  names  of  many  leading  physi- 
cians in  all  parts  of  the  world.  A  fourth  declaration  of  opinions,  which 
has  already  received  several  thousand  signatures,  is  now  (1905)  being 
circulated  and  reads  as  follows  :  — 

"  The  following  statement  has  been  agreed  upon  by  the  Council  of 
the  British  Medical  Temperance  Association,  the  American  Medical 
Temperance  Association,  the  Society  of  Medical  Abstainers  in  Ger- 
many, and  leading  physicians  in  England  and  on  the  continent.  The 
purpose  of  this  is  to  have  a  general  agreement  of  opinions  of  all  promi- 
nent physicians  in  civilized  countries  concerning  the  dangers  from 
alcohol,  and  in  this  way  give  support  to  the  efforts  made  to  check  and 
prevent  the  evils  from  this  source. 

"  In  view  of  the  terrible  evils  which  have  resulted  from  the  consump- 
tion of  alcohol,  evils  which,  in  many  parts  of  the  world,  are  rapidly 
increasing,  we,  members  of  the  medical  profession,  feel  it  to  be  our  duty, 
as  being  in  some  sense  the  guardians  of  the  public  health,  to  speak 


FOOD  AND  DIGESTION  l8l 

plainly  of  the  nature  of  alcohol,  and  of  the  injury  to  the  individual,  and 
the  danger  to  the  community  which  arise  from  the  prevalent  use  of 
intoxicating  liquors  as  beverages. 

"We  think  it  ought  to  be  known  that:  — 

"  i .  Experiments  have  demonstrated  that,  even  a  small  quantity  of 
alcoholic  liquor,  either  immediately  or  after  a  short  time,  prevents  per- 
fect mental  action,  and  interferes  with  the  function  of  the  cells  and 
tissues  of  the  body,  impairing  self-control  by  producing  progressive 
paralysis  of  the  judgment  and  of  the  will,  and  having  other  markedly 
injurious  effects.  Hence,  alcohol  must  be  regarded  as  a  poison,  and 
ought  not  to  be  classed  among  foods. 

"2.  Observation  establishes  the  fact  that  a  moderate  use  of  alcoholic 
liquors,  continued  over  a  number  of  years,  produces  a  gradual  deterio- 
ration of  the  tissues  of  the  body,  and  hastens  the  change  which  old 
age  brings,  thus  increasing  the  average  liability  to  disease  (especially  to 
infectious  diseases)  and  shortening  the  duration  of  life. 

''3.  Total  abstainers,  other  conditions  being  similar,  can  perform 
more  work,  possess  greater  powers  of  endurance,  have  on  the  average 
less  sickness,  and  recover  more  quickly  than  non-abstainers,  especially 
from  infectious  diseases,  while  they  altogether  escape  diseases  specially 
caused  by  alcohol. 

"4.  All  the  bodily  functions  of  a  man,  as  of  every  other  animal,  are 
best  performed  in  the  absence  of  alcohol,  and  any  supposed  experience 
to  the  contrary  is  founded  on  delusion,  a  result  of  the  action  of  alcohol 
on  the  nerve  centers. 

"  5.  Further,  alcohol  tends  to  produce  in  the  offspring  of  drinkers  an 
unstable  nervous  system,  lowering  them  mentally,  morally,  and  physi- 
cally. Thus,  deterioration  of  the  race  threatens  us,  and  this  is  likely 
to  be  greatly  accelerated  by  the  alarming  increase  of  drinking  among 
women,  who  have  hitherto  been  little  addicted  to  this  vice.  Since  the 
mothers  of  the  coming  generation  are  thus  involved,  the  importance 
and  danger  of  this  increase  cannot  be  exaggerated. 

"  Seeing,  then,  that  the  common  use  of  alcoholic  beverages  is  always 
and  everywhere  followed,  sooner  or  later,  by  moral,  physical,  and  social 
results  of  a  most  serious  and  threatening  character,  and  that  it  is  the 
cause,  direct  or  indirect,  of  a  very  large  proportion  of  the  poverty,  suf- 
fering, vice,  crime,  lunacy,  disease,  and  death,  not  only  in  the  case  of 
those  who  take  such  beverages,  but  in  the  case  of  others  who  are  un- 
avoidably associated  with  them,  we  feel  warranted,  nay,  compelled  to 
urge  the  general  adoption  of  total  abstinence  from  all  intoxicating 
liquors  as  beverages,  as  the  surest,  simplest,  and  quickest  method  of 
removing  the  evils  which  necessarily  result  from  their  use.  Such  a 
course  is  not  only  universally  safe,  but  is  also  natural. 


1 82  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

"  We  believe  that  such  an  era  of  health,  happiness,  and  prosperity 
would  be  inaugurated  thereby,  that  many  of  the  social  problems  of  the 
present  age  would  be  solved." 

REVIEW  QUESTIONS.  —  Chapter  VII.  1.  What  is  the  source  of 
the  heat  of  the  body ;  its  energy ;  its  growth  ?  2.  What  is  diges- 
tion ;  assimilation ;  oxidation  ;  excretion  ;  nourishment ;  nutrition  ? 
3.  Trace  energy  through  several  changes  of  form.  4.  Why  must 
heat  be  constantly  generated  in  the  body  ?  How  is  the  fuel  stored  ? 

5.  Mention  several  kinds  of  oxidation.       6.  Give  an  idea  of  the  amount 
of  heat  and  work  produced  by  the  body  in  one  day.       7.  Compare  the 
body  with  a  steam  engine  as  a  machine  for  doing  work.       8.  Show  how 
plants  support  animal  life.     What  enables  them  to  do  this  ?      9.  Does 
a  plant,  or  an  animal,  store  up  energy  ?    Which  expends  the  energy  ? 
10.  Describe  the  changes  that  take  place  in  a  body  deprived  of  food. 

1.  Name  the  four  kinds  of  food  stuffs.  Which  two  are  classed  to- 
gether as  fuel  foods?  2.  Which  food  builds  tissue?  3.  Which 
foods  aid  these  two  classes  in  their  work  ?  4.  Why  is  proteid  so 
important  among  food  stuffs?  5.  Name  the  sugars  with  their  sources. 

6.  State  the  sources  of  fat.      7.  Name  the  several  forms  of  proteids 
with   their  sources.      8.  Show   the  importance   of  taking  plenty   of 
water.       9.  Name  the  three  chief  wastes  resulting  from  the  vital  pro- 
cesses, and  the  organs  which  excrete  each  of  them.     Why  is  undigested 
material  rejected  by  the  alimentary  canal  classed  apart  ?      10.  Name 
the  sources  of  plant  food  ;  animal  food  ;  mineral  food. 

1.  What  weights  of  proteid  and  fuel  foods  are  needed  to  replace  the 
daily  waste  ?  2.  When  is  appetite  a  perfect  guide  ?  3.  What  are 
the  undesirable  extremes  in  selecting  food  ?  4.  How  may  intelligence 
be  a  source  of  economy  in  providing  food  ?  5.  Why  is  excess  or 
lack  of  proteid  worse  than  excess  or  lack  of  fuel  food  ?  6.  How  much 
(i)  proteid,  (2)  fat,  (3)  sugar  and  starch  are  needed  in  the  ration? 

7.  If  there  is  one  fourth  ounce  of  proteid  in  an  ounce  of  beans,  what 
weight  of  beans  must  be  eaten  to  obtain  four  ounces  of  proteid  ?     If 
there  is  one  fifth  of  an  ounce  of  proteid  in  an  ounce  of  lean  beef,  how 
many  ounces  of  beef  would  furnish  as  much  proteid  as  eight  ounces  of 
beans,  so  as  to  replace  half  the  beans  with  beef  ?     Name  starchy  and 
oily  foods  which  might  be  used  to  complete  the  ration.       8.  How  do 
the  following  peoples  obtain  the  right  proportions  of  the  food  stuffs : 
Scotch  ;  Irish  ;  Mexicans  ;  Arabs  ;  Asiatics  ?      9.   Give  a  summary  of 
digestion  in  the  mouth,  stomach,  and  small  intestine.      10.  Name  two 
parts  of  the  alimentary  canal  in  which  there  is  no  digestion.       11.  Trace 
a  piece  of  bread  from  the  time  it  is  eaten  until  it  is  assimilated  in  the 
cells.       12.  Does  hunger  show  the  condition  of  the  stomach  or  of  the 


FOOD  AND  DIGESTION  183 

cells  in  general  ?      13.  Describe  the  parts  of  which  a  tooth  is  composed 

14.  Name  the  teeth  in  one  quarter  of  the  mouth  in  order  from  the  front 
Which  teeth  are  lacking  in  the  temporary  set  ?      15.  What  do  you 
learn  by  studying  the  teeth  in  a  mirror  ?      16.  What  conditions  favor 
the  preservation  of  the  teeth  ? 

1.  Name  the  mechanical,  chemical,  and  organic  agencies  in  diges- 
tion. 2.  What  is  the  ferment  in  saliva  ?  How  much  faster  does  saliva 
flow  for  dry  food  than  for  moist  food  ?  3.  What  are  the  objections  to 
chewing  gum ;  chewing  tobacco  ?  4.  Describe  the  pharynx.  Name 
its  seven  openings.  5.  Describe  the  gullet;  the  act  of  swallowing. 
6.  Describe  the  advantages  of  munching  the  food,  as  shown  by  recent 
investigations  on  the  subject.  7.  Describe  the  structure  and  muscular 
action  of  the  stomach.  Describe  the  gastric  glands.  8.  State  the 
work  done  by  each  part  of  the  gastric  juice.  9.  Describe  the  action  of 
gastric  juice  upon  lean  meat ;  fat  meat.  10.  What  is  the  condition  of 
each  food  stuff  when  the  food  has  been  changed  to  chyme  ?  11.  De- 
scribe the  action  of  the  pylorus.  12.  What  is  the  structure  of  the 
small  intestine  ?  13.  Show  that  it  is  the  most  important  of  the  diges- 
tive organs.  14.  Describe  the  pancreas  and  the  action  of  its  ferments. 

15.  How  is  fat  emulsified  and  absorbed  ?      16.  How  are  digested  pro- 
teid  and  sugar  absorbed  ?      17.  What  is  the  position  of  the  liver  ? 
What  are  its  functions  ?      18.  Trace  the  course  of  the  colon  (Fig.  125). 
19.  Give   differences  of  opinion  about  humoring   the  stomach ;  raw 
foods;  stimulants;    drinking  at  meals;   times  for  eating;   quantity  of 
food,  etc.      20.  Why  should  not  all  people  eat  the  same  kind  of  food  ? 

1.  Man's  food  tube  was  originally  designed  for  what  kind  of  man  ? 

2.  What  is  a  simple  test  whether  a  food  was  eaten  by  early  man  ? 

3.  What  food  was  the  principal  support  of  early  man  ?     In  what  order 
were  the  other  foods  added  to  his  diet  ?      4.  State  four  valuable  quali- 
ties of  fruits  as  food.    Repeat  what  is  said  of  apples ;  bananas ;  peaches  ; 
cherries  ;  pineapples  ;  strawberries  ;  grapes ;  watermelons.      5.  Are  nuts 
very  nutritious  ?    Their  oil  is  in  what  state  ?    Give  two  reasons  for  prej- 
udice against  them.     What  is  said  of  pecans ;  almonds ;   chestnuts ; 
cocoanuts  ?      6.  Why  should  meat  be  thoroughly  cooked  ?     Discuss 
beef  tea ;  milk ;  butter ;  cheese ;  eggs ;  fish.      7.  Grains  are  of  value 
for  what  two  food  stuffs  ?     What  is  the  effect  of  prolonged  cooking  of 
grains  ?       8.    Discuss    the    food    value    of   the    various   vegetables. 
9.  Give  the  advantages  of  good  cooking  and  the  disadvantages  of  bad 
cooking.      10.  What  are  the  five  modes  of  cooking  ?     Describe  the 
five  methods,  with  the  precautions  to  be  observed  in  using  each  method, 
and  the  foods  suitable  to  be  cooked  by  each  method. 


CHAPTER  VIII 

THE  NERVOUS   SYSTEM 

Review  Questions  introducing  this  Subject.  —  What  is  a  cell  ? 
What  are  the  five  supporting  tissues  ?  What  are  the  two  master  tis- 
sues ?  Why  are  they  so  called  ?  Will  muscles  contract  by  their  own 
action  alone  ?  What  kind  of  cells  have  many  branches  ?  Where  is  the 
greatest  collection  of  nerve  cells  placed,  and  what  is  it  called  ?  Does 
the  food  ever  come  in  contact  with  the  salivary  glands  ?  When  you  look 
at  a  basket  of  apples,  the  sight  "  makes  your  mouth  water."  There 
must  have  been  a  connection  between  the  eye  and  the  mouth.  What 
makes  this  relation  possible  ?  What  two  tissues  enable  the  skin  to 
blanch  and  to  blush  ?  Do  the  different  organs  share  the  blood  in  the 
same  proportions  at  all  times  ?  How  can  this  proportion  be  changed  ? 
How  is  the  brain  protected  from  injury  ?  How  is  the  spinal  cord  pro- 
tected ?  Is  the  hole  for  the  spinal  cord  through  the  main  body  of  the 
vertebra,  or  behind  the  main  body  ? 

An  Instance  of  the  Wonderful  Harmony  of  the  Bodily 
Functions. — When  one  uses  the  muscles  of  the  legs  in 
running  rapidly,  before  he  has  gone  many  steps  the  lungs 
begin  to  expand  with  deep  breaths  in  order  to  supply  more 
oxygen  to  the  active  muscles.  The  heart  soon  pumps 
more  vigorously  to  send  the  blood  bearing  this  oxygen  to 
the  place  where  it  is  needed.  The  great  oxidation  going 
on  in  the  muscles  of  the  runner  tends  to  overheat  the 
body,  so  before  many  minutes  have  passed  the  sweat 
tubes  begin  to  pour  out  the  perspiration  which,  by  its 
evaporation,  cools  the  body.  If  the  runner  keeps  on 
running  so  long  that  the  lungs  and  heart  cannot  keep  up 
a  sufficient  supply  of  oxygen  to  replace  the  large  amount 
so  rapidly  consumed,  the  muscles  begin  to  ache  and  the 

184 


THE  NERVOUS  SYSTEM 


185 


runner  is  warned  that  he  must  stop,  or  be  in  danger  of 
straining  or  injuring  some  part  of  his  body.  This  beauti- 
ful harmony  in  the  work  of  the 
various  organs  is  made  possible  by 
the  nervous  system. 

Other  Examples  of  this  Harmony. 
—  Strike  suddenly  at  the  eye  of 
another,  and  the  lids  fall  to  protect 
it,  and  the  hands  rise  to  ward  off 
the  blow.  If  a  grain  of  dust  gets 
into  the  eye,  the  tear  glands  form 
tears  to  wash  it  out.  If  you  touch 
the  hand  unexpectedly  to  a  hot  iron, 
the  muscles  of  the  arm  jerk  the 
hand  away.  Tickle  the  foot  of  a 
sleeping  person,  and  the  muscles 
of  the  leg  pull  it  away.  If  the 
human  being  were  merely  an  as- 
semblage of  working  organs,  these 
organs  might  act  independently, 
and  there  would  be  such  confusion 
that  the  body  would  be  powerless, 
and  would  soon  go  to  pieces.  It 
is  fortunate  that  a  means  is  pro- 
vided to  make  the  organs  work 
together  for  the  common  good 
(Fig.  141). 

The  Need  of  Nerve  Centers  as  well 
as  Nerves.  —  If  there  were  no  cen- 
tral office  in  a  telephone  system  of  one  thousand  sub- 
scribers, then  every  subscriber,  in  order  to  communicate 
with  every  other  subscriber,  would  need  one  thousand 
wires  running  into  his  house;  all  together,  there  would 


FIG.  141.  — LARGER  NERVE? 
near  surface  of  right  arm. 


1 86 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


'ifts- 


-Me 


have  to  be  several  hundred  thousand  (499,500)  wires.  With 
A  ft  a  central  office  only  one  thousand 

are  needed. 

As  a  telephone  system  has  cen- 
tral offices,  so  our  nervous  systems 
have  nerve  centers.  Nerve  centers 
contain  nerve  cells.  Although  there 
are  some  subordinate  nerve  centers 
in  the  spinal  cord,  the  great  nerve 
center  of  our  bodies  is  in  the  skull, 
and  is  called  the  brain.  Without 
nerve  centers  the  nervous  system 
would  not  deserve  the  name  of 
system. 

The  nervous  system,  unlike  a  tele- 
phone system,  has  other  duties  be- 
sides allowing  communication.  It 
enables  us  to  think,  and  after  reflec- 
tion, to  will  and  to  act  by  control- 
ling the  various  organs. 

The  Units  of  which  the  Nervous 
System  is  Constructed.  —  A  nerve 
cell  with  all  its  branches,  or  fibers,  is 
called  a  neuron  (see  Fig.  142).  Neu- 
rons are  the  units  that  compose  the 
nervous  system.  You  learned  that 
the  living  substance  in  cells  is  called 
protoplasm.  The  cell  branches,  or 
fibers,  contain  an  almost  transparent, 
FIG.  142.— Showing  a  NEU-  jelly  like  protoplasm,  possessing  the 

RON,  ,4,  or  nerve  cell  with  ,  .     , 

all  its  parts -dendrites,     most  marvelous  and  varied  powers 

cell  body,  and  axon;  B,  a       of    any    known     Substance,    for     the 
portion  of  a  white  fiber 

highly  magnified,  (jegi.)     nerve  cells  are  the  seat  of  the  mind 


THE  NERVOUS  SYSTEM 


is? 


Nerve  Cells  and  Fibers.  — The  many  branches  of  nerve 
cells  make  them  the  most  remarkable  of  all  cells  for  irregu- 
larity in  shape.  Since  the  protoplasm  of  the  cell  continues 
into  the  fibers,  it  is  plainly  wrong  to  consider  the  nerve 
cell  as  something  apart  from  its  fibers.  It  is  not  a  com- 
plete cell  without  them.  A  cell  usually  has  many  short 
branches  called  dendrons  or  dendrites  (see  Fig.  142)  for 
communicating  with  near-by  cells,  and  one  long  branch 
called  an  axon  (Fig.  142)  for  communicating  with  distant 
parts.  The  axons  form  the  fibers  that  go  to  the  skin, 
muscles,  and  other  organs.  The  long  axons  go  all  over 
the  body  and  are  often  bound  together  into  visible  cords 
called  nerves,  or  nerve  trunks  (see  Fig.  75, 
photomicrographs,  p.  77). 

As  the  various  parts  of  a  city  are  in 
communication  by  means  of  telephone 
wires,  the  different  parts  of  the  body  are 
in  constant  communication  by  means  of 
these  living  threads.  The  nerve  cell  which 
sends  the  impulse  corresponds  to  the  bat- 
tery which  sends  the  electricity ;  the  nerve 
fiber  corresponds  to  the  wire. 

White  and  Gray  Fibers  (Fig.  143).  — If 
a  fiber  has  a  fatty  covering  surrounding 
the  thread  of  protoplasm,  it  is  white  and  FlG  143._,ia  white 
glistening,  and  is  called  a  white  fiber.  If  fiber  with  its  fattv 
it  is  without  this  fatty  covering,  it  is  gray  two  gray  fibers 
in  color  and  is  called  a  gray  fiber.  Both  (without  sheath)' 
kinds  of  fibers  have  connective  tissue  on  the  outside  to 
strengthen  them.  If  we  let  a  lead  pencil  represent  a  white 
fiber,  the  lead  corresponds  to  the  core,  or  axis,  of  proto- 
plasm ;  the  wood  corresponds  to  the  white,  shiny  fat  that 
surrounds  it;  and  the  varnish  corresponds  to  connective 


1 88 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


FIG.  144.— A 
GANGLION. 


tissue  on  the  surface  of  the  fiber.  A  number  of  white 
fibers  together  make  a  white  mass  that  is  called  white 
matter.  The  axis  of  a  white  fiber,  of  course,  is  not  white. 
A  mass  of  cells  or  of  gray  fibers  is  called  gray  matter. 

Feeling  Cells  and  Working  Cells.  —  Nerve  cells  may  be 
divided  into  two  classes  :  sensory  cells,  which  feel  or  receive 
impressions ;  and  motor  cells,  which  send  out  impressions  to 
the  working  organs.  Those  fibers  which  carry  impressions 
to  the  receiving  cells  are  called  sensory  fibers ;  those  which 
carry  impulses  from  the  cells  to  the  working 
organs  are  called  motor  fibers. 

A  Ganglion  and  a  Nerve  Center.  —  Nerve 
cells  are  not  scattered  uniformly  in  nervous 
tissue,  but  are  gathered  into  groups.  A  group 
of  nerve  cells  is  called  a  ganglion  (Fig.  144). 
One  or  more  ganglia  having  a  single  function, 
such  as  to  control  the  muscles  of  breathing, 
form  what  is  called  a  nerve  center.  The  brain  consists  of 
a  number  of  nerve  centers  with  their  connecting  fibers. 

Structure  of  the  Spinal  Cord.  —  The  nerve  fibers  from 
nearly  all  over  the  body  lead  to  cells  situated  in  a  large. 
cord  in  the  spinal  column  called 
the  spinal  cord.     The  spinal  cord 
is  separated  by  a  deep  fisstire  al- 
most into  halves  (Fig.  145).    The 
cells  are  situated  in  the  central 
portion  of  each  half,  and  the  two 
masses  of  gray  matter  thus  formed 
are  connected  by  a  narrow  isth-  FlG.  I4S>  _  CROSS  SECTION  OF 
mus  of  gray  matter.     The  outer       SPINAL  CORD,  showing  area 

of  gray  matter  (dark). 

part  of  the  cord  consists  chiefly  of 

white  fibers.     The  white  matter  is  thus  on  the  outside  of 

the  cord  (Fig.  145).     The  brain,  unlike  the  cord,  has  the 


p.Tt. 


THE  NERVOUS  SYSTEM  189 

gray  matter  on  the  outside  and  the  white  matter  on  the 
inside. 

The  Work  of  the  Spinal  Cord.  —  There  are  two  functions 
of  the  cord  :  reflex  action  and  transmission  of  impulses 
from  the  body  to  the  brain.  Reflex  action  is  action  that 
takes  place  without  the  aid  of  the  will. 

Reflex  Action.  —  This  action  never  begins  in  the  cord, 
but  at  the  outer  end  of  a  sen- 
sory fiber,  usually  located  in  the 
skin.  The  impression  goes  to 
the  cord  along  a  sensory  fiber. 
It  is  received  in  a  sensory  cell  and 
transferred  to  a  motor  cell  which 
sends  back  an  impulse  along  a 
motor  fiber  to  a  muscle  ;  the  mus- 

(a) 

cle  contracts  and   the   action  is  •{tJ!SSs?LECELL* 

complete  (see  Fig.  146).      There  FIG.  i46._  NERVE  CURRENT  IN 
are  always  two  nerve  cells  con-       REFLEX  ACTION,  showing  that 

two  cells  are  necessary  for  it. 

cerned    in   every   reflex    action. 

The  greater  part  of  the  nervous  energy  expended  in  the 

body  is  used  in  producing  the  numberless  reflex  actions. 

Reflex  Action,  Consciousness,  and  Will.  —  Usually  not  all 
of  the  force  of  the  impulse  is  transferred  to  the  motor  cell. 
The  sensory  cell  by  means  of  another  of  its  many  branches 
may  transfer  part  of  the  impulse  to  a  cell  which  sends  it  to  the 
brain.  Hence  a  reflex  act  is  not  necessarily  an  unconscious 
one.  If  you  unintentionally  touch  the  hand  to  a  hot  stove- 
pipe, you  may  be  conscious  of  the  pain  and  the  involuntary 
jerking  away  of  the  hand  at  the  same  time.  Reflex  action 
takes  place  during  sleep  as  readily  as  when  we  are  awake. 
This  may  be  proven  by  tickling  the  foot  of  a  sleeping 
person.  Sometimes  the  will  may  inhibit  or  prevent  a 
reflex  act.  Many  reflex  acts  occur  in  spite  of  the  effort  of 


IQO  2*£SSONS  IN  HYGIENIC  PHYSIOLOGY 

the  will  to  prevent  them.  You  cannot  always  keep  from 
closing  your  eyes  when  some  one  strikes  at  you,  even  if 
from  the  other  side  of  a  plate  glass  window,  and  you  know 
there  is  no  danger.  Sneezing  is  a  reflex  act  and  you  can- 
not prevent  it,  even  if  you  try  to  do  so  for  fear  of  disturb- 
ing the  sleep  of  another.  The  forming  of  saliva  and  other 
secretions  are  reflex  acts.  Reflex  acts  are  qtiicker  than 
conscious  acts.  An  eighth  of  a  second  is 
about  the  time  required  for  a  person  to 
press  an  electric  button  after  seeing  a 
signal ;  a  reflex  act  may  occur  in  a  shorter 
time. 

The  Brain  consists  of  Three  Chief  Parts. 
—  (i)  There  is  an  enlargement  at  the  top 
of  the  spinal  cord  called  the  medulla,  or 
the  medulla  oblongata.  It  may  be  looked 
upon  as  the  part  of  the  spinal  cord 
within  the  skull  (see  Figs.  147,  148,  153). 
(2)  Above  the  medulla  is  the  cerebellum, 
or  little  brain.  (3)  The  cerebrum,  or  large 
brain,  fills  all  the  skull  except  the  small 
part  occupied  by  the  medulla  and  cerebel- 
lum. Does  the  cerebrum  cover  the  cere- 
bellum on  top?  (See  Figs.  147,  148.) 

The  work  of  the  medulla  is  chiefly  to  con- 
trol  the  vital  functions  (see  Figs.  148,  153). 
Here  are  located  the  centers  for  regulating  ' 

• 

FIG.  147.  —  BRAIN  the  breathing,  the  heart  beat,  the  size  of 
AND  SPINAL  CORD.  ^  ^^  vesseis  (thus  regulating  nutrition), 

and  also  the  less  important  centers  that  control  swallowing, 
secretion  of  saliva,  and  vomiting.  The  center  for  breathing 
is  sometimes  called  the  vital  knot,  because  although  the 
cerebrum  and  cerebellum  may  be  removed  from  an  animal 


THE  NERVOVS  SYSTEM  IQI 

without  causing  immediate  death,  the  slightest  injury  to 
the  vital  knot  kills  the  animal  at  once.  In  cases  of  hanging, 
death  is  caused  by  injury  to  this  center. 

Automatic  Action The  center  called  the  vital  knot  is 

not  said  to  regulate  the  breathing  reflexly,  but  automati- 
cally. Reflex  acts  start  in  the  skin  ;  automatic  acts  start  in 
the  interior  of  the  body.  The  condition  of  the  blood  regu- 
lates the  breathing  automatically.  If  too  much  carbon 
dioxid  accumulates  in  the  blood,  this  excites  the  vital 
knot  which  sends  out  stronger  impulses  to  the  respiratory 
muscles.  Deeper  breathing  follows,  which  purifies  the 
blood,  and  the  breathing  is  then  quiet  until  an  excess  of 
carbon  dioxid  occurs  again. 

The  cord  controls  chiefly  reflex  action ;  the  medulla  con- 
trols chiefly  automatic  action ;  the  cerebellum  controls  chiefly 
coordinate^  or  harmonizing,  action ;  the  cerebrum  controls 
the  purely  voluntary  acts,  for  it  is  the  seat  of  consciousness 
and  thought.  The  medulla,  like  the  cord,  has  the  gray 
matter  on  the  inside  (Fig.  147). 

Structure  of  the  Cerebellum. 
— The  cerebellum,  like  the  cere- 
brum, has  the  gray  matter  or 
cells  on  the  outside.  The  gray 
matter  is  folded  into  furrows 
that  are  not  nearly  so  winding 
as  the  folds  in  the  cerebrum 

(see     Fig.      154).       The    fibers    FIG.  148.- THE  BRAIN  (cerebrum, 

cerebellum,  medulla). 

going  to  the  surface  cells  have 

a  branched  arrangement  called  the  arbor  vitce^  or  tree  of 
life,  which  is  shown  where  the  cerebellum  is  cut.  The 
cerebellum,  like  the  cerebrum,  is  deeply  cleft  and  thus 
divided  into  halves,  called  hemispheres,  connected  by  a 
band  of  white  matter. 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


The  work  of  the  cerebellum  is  to  aid  the  cerebrum  in 
controlling  the  muscles.  It  coordinates  the  muscular  move- 
ments, that  is,  it  makes  the  muscles  act  at  the  right  time 
and  with  due  force  in  complex  acts,  such  as  standing, 
walking,  talking.  A  man  could  strike  just  as  hard  with- 
out the  action  of  the  cerebellum,  but  he  would  not  be 
likely  to  hit  what  he  aimed  at.  A  drunken  man  staggers 
and  fails  to  control  the  muscles  in  walking  because  the 
alcohol  has  caused  the  blood  to  collect  and  congest  around 


FlG.  149.  —  ARTERIES  on  the  surface  of  the  cerebrum.     (Cunningham.) 


the  cerebellum  and  press  upon  it.  When  the  cerebellum 
of  a  person  is  injured  by  accident,  he  staggers  like  a 
drunken  man. 

Structure  of  the  Cerebrum.  —  Lining  the  skull  and  cov- 
ering the  cerebrum  are  found  several  membranes  which 
inclose  a  lymphlike  fluid.  Thus  a  kind  of  water  bed  is 
made  which  surrounds  the  soft  and  delicate  cerebrum  and 
protects  it  from  jars.  Within  the  membranes  are  numerous 
blood  vessels  which  plentifully  supply  the  cerebrum  with 
blood  (Fig.  149).  The  gray  matter,  or  cell  mass  of  the 


THE  NERVOUS  SYSTEM 


193 


150.— ASSOCIATION  FIBERS. 


cerebrum,  forms  a  surface  layer,  called  the  cortex  ("  bark  "), 
about  one  eighth  of  an  inch  thick.  This  gray  layer  is 
deeply  folded,  the  folds,  or  convolutions,  being  separated  by 
deep  furrows,  some  of  them  an  inch  deep  (see  Fig.  158). 
Thus  the  area  of  the  surface 
layer  is  increased  to  several 
times  what  it  would  be  if 
smooth.  The  highest  func- 
tions of  the  brain  take  place 
in  the  gray  layer.  The  larger 
part  of  the  cerebrum  consists 
of  the  white  matter  which  is 
within  the  gray  matter.  It  consists  of  fibers  which  con- 
nect the  cells  in  the  gray  matter  with  each  other  and  with 
important  interior  ganglia  at  the  base  of  the  cerebrum 
(Figs.  150,  151,  158).  These  ganglia  are  situated  just  in 
front  of  the  cerebellum,  and  above  the  medulla,  and  serve 

to  connect  the  medulla,  cere- 
bellum, and  cerebrum  with 
each  other. 

The  cerebrum  comprises 
nearly  seven  eighths  of  the 
weight  of  the  brain.  A  deep 
fissure  divides  it  into  the  right 
and  left  cerebral  hemispheres. 
FIG.  151.  — SENSORY  AND  MOTOR  A  band  of  white  matter  con- 
nects the  hemispheres  (see 

Fig.  158).  There  are  several  cavities  in  the  interior  of 
the  brain  filled  with  the  same  kind  of  lymphlike  fluid 
that  surrounds  it.  Two  of  them  are  shown  in  Figure  158. 
Spinal  and  Cranial  Nerves.  —  The  nerves  from  the 
spinal  cord  go  out  through  notches  between  the  vertebrae 
in  thirty-one  pairs,  called  the  spinal  nerves  (Fig.  147). 


IQ4 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


ace  Sensory 
ace  Motions 

Taste 


Since   there   are  only  twenty-four  vertebrae,  some  of  tbe 
spinal  nerves  go  out  through  holes  in  the  sacrum.     The 

cranial  nerves 
leave  the  brain 
through  holes  in 
the  cranium,  or 
skull  There  are 
twelve  pairs  of 
them  (see  Fig. 
152).  The  tenth 
pair  is  shown  in 
colored  Figure 
1 6. 

Functions  of 
the  Cerebrum. — 
The  cerebrum  is 
the  seat  of  con- 
sciousness and 
thought,  and  of 
all  activity  con- 
trolled by  the 
will.  It  also  presides  over  the  work  of  the  lower  netve 
centers  in  the  spinal  cord,  medulla,  and  cerebellum. 

It  receives  sensory  messages  from  all  parts  of  the  skin 
and  through  the  special  senses.  It  sends  out  motor  mes- 
sages to  all  the  voluntary  muscles,  and  more  indirectly 
to  the  involuntary  muscles.  The  cerebral  fibers  are  of 
three  kinds:  sensory,  associational,  and  motor  (Figs.  150, 
151)  It  is  estimated  that  the  cerebrum  alone  contains 
9,200,000,000  cells. 

Parts  of  the  Cerebrum  that  receive  Sensory  Messages.  — 
It  was  discovered  a  few  years  ago  that  certain  parts  of  the 
brain  have  definite  duties  to  perform.  The  nerve  fibers 


-  Spinal  Cortl 
1st  Spinal  Nerve 
2d  Spinal  Nerve 


FIG,  152.  — DIAGRAM  OF  THE  TWELVE  CRANIAL 

NERVES. 


THE  NERVOUS  SYSTEM 


195 


that  come  from  the  eyes  lead  to  the  lower  back  part  of 
the  cerebrum  (see  Fig.   154).     Thus,  although   the   eyes 


Cerebrum 


are  in  front,  we  see  with  the 
back  part  of  our  heads.  If  you 
fall  and  strike  upon  the  back 
part  of  the  head,  you  may  "  see 
stars,"  although  there  are  no 
stars  to  see.  Disease  in  this 
part  of  the  brain  may  result  in 
blindness,  though  the  eyes  are 
still  sound.  The  impressions 
from  the  ears  in  hearing  are 
received  just  above  the  ears  in 
the  convolutions  at  the  temples. 

Smells  are  perceived  with  the  FIG.   153. —  THE  LOBES  OF  THE 
,  e     ,  .  RIGHT  SIDE  OF  BRAIN  and  their 

base  of  the  cerebrum  toward       functions.    (jegi.) 

the  front.  The  sPeech   center  is   true  only  for  left- 

handed  persons.     Medulla  is  marked 

Parts  of  the  Cerebrum  that      "Buib.» 
send  Motor  Messages.  —  The  top   part  of  the   cerebrum 

sends  out  the  motor 
messages.  The  par- 
ticular part  that  con- 
trols the  arms,  legs, 
trunk,  etc.,  have  been 
mapped  out  (see  Fig. 
154).  It  was  noticed 
by  a  surgeon  that  a 
certain  child  with  epi- 
lepsy always  had  a 
twitching  of  the  thumb 
before  an  attack  came 

^        A 


FIG.  154.  — MOTOR  AND  SENSORY  AREAS  OF  LEFT 
HFMISPHERE.     Speech  center  marked  "  Lips  "      of   the   skull    Over  the 


ig6 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


center  that  controls  the  thumb  was  lifted  up,  and  a  small 
tumor  was  found.  This  was  removed  and  the  skull  closed, 
and  the  child  had  no  more  attacks  of  the  disease.  The 
speech  center  is  in  the  lower  front  part  of  the  motor 
area  on  the  left  side  (Fig.  153).  A  blow  upon  that 
part  of  the  head  may  cause  a  blood  clot  there,  and  until 
the  clot  is  removed  by  a  surgeon  or  by  natural  healing, 
the  person  is  without  the  power  to  speak.  Since  the 

sensory  center  for  hear- 
ing is  uninjured,  he  can 
understand  what  is  said 
to  him;  and  since  the 
motor  center  for  the 
hand  is  unhurt,  he  can 
converse  with  others  by 
writing  his  replies. 

Relation  of  the  Cere- 
brum to  the  Lower  Cen- 
ters. —  The  ganglia  of 
the  lower  animals  con- 
trol their  simple  ac- 
tivities; but  the  more 
complex  nervous  sys- 
tem of  man  is  needed 

to   regulate   his  varied 
FIG.  155. —  PATH   OF  NERVE  CURRENT  in  ... 

voluntary  act ;  arrows  show  its  direction,  as     activities    of    mind    and 

follows:  body.     As  you  learned, 

Skin  (G)s  cord,  brain,  cord,  muscle  (C).     Why  can  a 
fowl  jump  after  its  head  is  cut  off?    Can  it  breathe?       theSC     activities     are      of 

several  kinds,  —  reflex,  automatic,  coordinate,  and  volun- 
tary. A  manufactory  has  more  complex  work  than  a 
shop.  A  man  with  a  shop  may  enlarge  it  into  a  factory 
and  leave  trained  assistants  in  charge  of  the  different 
shops,  keeping  only  the  general  management  for  himself. 


THE  NERVOUS  SYSTEM 

If  he  should  cease  to  control  his  assistants  entirely,  the 
work  of  the  factory  would  soon  be  in  disorder.  If  the 
manager  should  try  to  direct  everything,  he  would  become 
exhausted.  So  the  cerebrum,  the  seat  of  the  will  and  the 
reason,  leaves  the  centers  in  the  spinal  cord,  medulla,  and 
cerebellum  to  do  most  of  the  work.  If  the  mind  wishes 
the  hand  to  move  and  grasp  the  hand  of  a  friend,  the 
motor  center  in  the  cerebrum  sends  a  message  to  the  cere- 
bellum ;  and  if  the  cerebellum  has  been  well  trained,  the 
act  is  accurately  performed  (Fig.  155). 

A  more  perfect  wisdom  than  that  of  the  mind  is  in  the 
lower  nerve  centers.  The  reason  and  the  will  control  the 
lower  centers  through  the  cerebrum,  but  the  control  is  very 
limited.  It  is  well  that  this  is  so,  not  only  for  the  relief 
of  the  cerebrum,  but  for  the  safety  of  the  body.  Can  you 
change  the  rate  of  the  heart  beat  by  the  exercise  of  the 
will?  Can  you  blush  at  will,  or  prevent  the  flushing  of 
the  capillaries  when  you  are  embarrassed,  or  when  you 
go  close  to  a  hot  fire?  It  is  impossible  for  a  person  to 
commit  suicide  by  holding  the  breath.  What  change  in 
the  blood  would  soon  force  a  breath  to  be  taken  ?  Repeat 
the  two  examples  of  reflex  action  triumphing  over  the 
will  which  were  given  in  a  preceding  paragraph. 

THOUGHT  QUESTIONS.  —  Clothing  at  Neck  and  Waist.  The  neck  is 
very  [flexible  or  inflexible?].  It  is  healthier  [with  or  without?]  cover- 
ing. Stiff  or  high  neck  clothing  [destroys  or  preserves  ?]  its  beautiful 
curves,  and  makes  the  neck  [skinny  or  full  ?]  and  makes  one  [more  or 
less?]  apt  to  take  cold.  How  may  clothing  cause  backache  ?  (p.  201.) 

The  most  flexible  portion  of  the  trunk  is  the .  I  find  by  meas- 
uring with  a  tape  line,  that  the  circumference  of  my  waist  is inches 

more  with  the  lungs  expanded  than  when  they  are  contracted.  This  is 

called  waist  expansion.  My  waist  expansion  is  inches.  If  I 

have  my  clothing  cut  to  fit  the  larger  waist  measure,  and  support  it  by 
the  waist,  its  weight  will  cause  it  to  slip  when  the  waist  contracts  in 
breathing.  If  cut  to  fit  the  smaller  waist  measure,  the  cannot 


198  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

and  my  breathing  will  be .     The  [shoulder  or  waist?]  is  made 

mostly  of  tough  bone  and  muscle.     It  contains  no  delicate  vital  organs  ; 

it   does  not  expand  or   contract ;    it  is   horizontal,   while  the is 

vertical.     Therefore  the is  better  for  a  support  to   the  clothing 

than. the .     The  seven  vital  organs   at  the   waist  are  the  st , 

1 ,  sp ,  two  k ,  p ,  and  a  portion  of  the  large . 

The  ganglionic  or  sympathetic  portion  of  the  nervous 
system  controls .  the  viscera  (vis1  se-ra\  or  internal  organs. 
The  nerves  that  go  to  the  viscera  branch  off  from  the 
spinal  nerves  not  far  from  the  spinal  column,  and  enter  a 
row  of  ganglia  on  each  side  of  the  spine  (see  Fig.  156). 
Each  ganglion  is  connected  by  nerves  with  the  one  above 
and  below  it,  so  that  they  appear  like  two  knotted  cords 
suspended  on  each  side  of  the  spinal  column  and  tied 
together  below;  for  both  chains  of  ganglia  end  in  the 
same  ganglion  in  the  pelvis.  Some  of  the  fibers  from  the 
spinal  cord  pass  through  these  ganglia  on  their  way  to 
the  viscera.  The  spinal  cord  and  brain  taken  together 
are  sometimes  called  the  cerebro-spinal  system.  The  fibers 
which  go  through  the  double  chain  of  ganglia  are  some- 
times called  the  ganglionic  or  sympathetic  system.  But 
the  division  is  largely  artificial. 

Why  these  Nerves  are  called  the  Sympathetic  System.  — 
These  nerves  after  leaving  the  double  chain  of  ganglia 
form  many  intricate  networks  of  ganglia  and  fibers.  Each 
network  is  called  a  plexus  (Fig.  156).  The  largest  of 
the  plexuses  is  just  back  of  the  stomach,  and  is  called  the 
solar  plexus.  A  blow  upon  the  stomach  may  paralyze  this 
plexus  and  cause  sudden  death.  The  plexuses  and  fibers 
connect  the  viscera  so  perfectly  that  one  organ  cannot  suffer 
without  the  others  suffering  or  sympathizing  with  it.  An 
overloaded  stomach  causes  the  heart  to  beat  faster  and 
send  it  more  blood ;  a  loss  of  appetite  usually  accompanies 
illness  and  allows  the  stomach  to  rest.  This  sympathy  is 


THE  NERVOUS  SYSTEM 


199 


necessary,  for  if  one  or- 
gan is  diseased,  the  others 
do  not  continue  to  work 
and  tax  the  strength  of 
the  ailing  organ.  For  an 
instance  of  organs  acting 
in  sympathy  during  a  time 
of  increased  activity,  refer 
to  page  184. 

How  the  Sympathetic 
and  Cerebro-spinal  Nerves 
Differ.  —  The  visceral 
nerves  (i)  contain  mostly 
gray  fibers;  (2)  pass 
tkrottgh  ganglia  after  leav- 
ing the  spinal  cord;  (3) 
control  the  unconscious 
activities  of  the  body; 
(4)  pass  to  organs  which 
contain  slow-acting  invol- 
untary muscles  ;  ( 5  )  trans- 
mit impulses  slowly  (about 
twenty  feet  per  second). 

The  cerebro-spinal 
nerves  (i)  contain  only 
white  fibers;  (2)  do  not 
pass  through  ganglia  after 
leaving  brain  and  spinal 
cord ;  (3)  control  the  con- 
scious activities  of  the 

,      ,        /   %  ,.   ,,  FIG.  156.  — THE  SYMPATHETIC,  OR  CAN- 

body;   (4)  pass  chiefly  to      GLIONIC  SYSTEM,  showing 'the  row  of 

sense    Organs    and    Quick-        ganSlia  connected  with  the  spinal  nerves 

of  the  right   side,  the  plexus  at  heart,  at 
acting  voluntary  muscles  J        stomach  (solar),  and  intestine. 


2OO  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

(5)  transmit  impulses  at  the  rate  of  about  one  hundred 
feet  per  second. 

How  the  Sympathetic  System  automatically  cares  for 
the  Body.  —  The  pleasant  taste  of  food  causes  a  reflex 
stimulation  of  the  salivary  glands  and  the  saliva  is  de- 
posited to  begin  digestion.  When  the  food  goes  into  the 
stomach  and  intestines,  their  muscular  walls  are  automati- 
cally stimulated  to  contract,  and  peristalsis  begins  and  the 
gland  cells  of  those  organs  form  the  needful  digestive 
fluids.  The  digested  food  passes  into  the  blood  vessels, 
and  the  beating  of  the  heart  and  the  size  of  the  blood 
vessels  are  regulated  through  certain  ganglionic  nerves  (the 
vasomo'tors)  that  the  food  may  be  properly  distributed  to 
the  tissues.  If  the  body  becomes  too  warm,  the  same  set 
of  nerves  takes  less  stimulus  to  the  muscles  in  the  walls  of 
the  arteries  near  the  surface.  The  skin  becomes  red  and 
heat  escapes  into  the  air  from  the  warm  blood.  At  the 
same  time,  the  cells  lining  the  sweat  glands  are  stimulated 
to  increased  secretion.  If  the  body  becomes  too  cold,  the 
skin  becomes  pale  and  dry,  and  the  heat  of  the  body  is 
economized.  At  a  flash  of  bright  light,  the  pupils  of  the 
eyes  slowly  become  smaller,  for  the  muscles  of  the  iris  are 
involuntary  and  are  under  the  control  of  ganglionic  nerves. 

Usually  the  ganglionic  nerves  care  for  the  vital  organs 
without  consulting  the  mind,  but  sometimes  complaints  and 
warnings  have  to  be  sent  to  the  cerebrum.  A  person  may 
eat  so  imprudently  that  the  food  tube  is  unable  to  do  its 
work.  Colic  and  cramps  and  vomiting  may  bring  relief. 
If  a  boy  runs  so  long  as  to  endanger  his  body,  a  pain  in 
the  heart  warns  him  to  stop.  "Heartburn"  has  no  con- 
nection with  the  heart ;  it  is  caused  by  the  stomach,  and 
is  a  warning  against  eating  too  much  or  eating  indigestible 
things  next  time.  It  is  called  heartburn  either  because 


THE  NERVOUS  SYSTEM  2OI 

many  people  think  the  heart  is  where  the  stomach  is 
(see  Fig.  94),  or  because,  although  not  refined  enough  to 
keep  from  eating  voraciously,  they  think  themselves  too 
refined  to  refer  to  the  digestive  organs.  Backache  in 
women  is  usually  caused  by  the  abdominal  organs  being 
pushed  downward  by  a  tight  corset  or  other  clothing  sus- 
pended from  the  waist.  This  causes  the  sympathetic 
ganglia  to  pull  upon  their  attachments  at  the  spine,  and 
backache  results. 

The  mind  is  only  notified  of  important  disorders  in  the 
viscera,  and  any  complaint  from  them  should  be  promptly 
heeded.  On  the  other  hand,  unusually  strong  activity  of 
the  brain  may  affect  this  system  of  nerves.  Examples: 
embarrassment  causes  blushing;  the  face  becomes  pale 
with  fear ;  sadness  interferes  with  digestion  and  may  take 
away  the  appetite. 

THOUGHT  QUESTIONS. — The  Body  is  wisely  Made.  1.  Name 
four  provisions  for  repair  of  accidental  or  unusual  injuries  to  the  body 
(pp.  24,  48,  92) .  2.  State  four  facts  in  anatomy  showing  provisions  for 
protection  (pp.  1 6,  42,  255).  3.  State  four  similar  facts  in  physiology 
(pp.  67,91,  117).  4.  Name  four  provisions  for  convenience  in  use 
(pp.  50,  60,  240).  5.  Name  four  devices  used  in  machinery,  examples 
of  which  occur  in  the  body  (pp.  81,  140,  also  Fig.  169).  6.  Name 
three  devices  of  architecture  found  in  the  body  (Figs.  37,  43,  57). 

HYGIENE  OF  THE   NERVOUS  SYSTEM 

Source  of  Nerve  Strength. — The  health  of  the  nerves 
depends  upon  a  free  supply  of  pure,  nutritious  blood. 
Nearly  one  fifth  of  the  blood  goes  to  the  brain.  Two  of 
the  larger  arteries  that  take  blood  to  the  brain  (the  carotid 
arteries)  are  shown  on  Plate  XIII.  It  is  clear  that  the 
brain  cannot  give  out  energy  until  it  has  first  received  it ; 
the  blood  supplies  energy  to  the  brain.  A  rested  cell  is  full 
of  nourishment ;  a  tired  cell  is  shriveled  (see  Fig.  157). 


2O2 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


Sleep.  —  During  waking  hours  energy  is  used  up  faster 
than  it  is  stored  in  the  cells,  and  the  tissues  are  worn  out 
faster  than  new  cells  are  formed  to  repair  them.  During 
sleep  the  opposite  is  true  ;  repair  is  more  rapid  than  waste. 
During  sleep  the  muscles  are  strengthened,  the  breathing 
is  less,  the  heart  beats  more  slowly,  less  heat  is  produced, 
digestion  is  slower,  less  blood  goes  to  the  brain  ;  but  above 
all,  the  nervous  system  has  an  opportunity  to  recuperate 
from  the  constant  activity  of  waking  hours.  The  eye  and 
the  ear  are  rested  by  darkness  and  silence.  Sleep  at  night 

is  more  refreshing  than  sleep 
in  the  daytime.  Why  is  it 
necessary  to  be  more  warmly 
protected  by  clothing  or  bed 
covering  when  asleep  than 
when  awake  ? 

Practical  Suggestions.  — 
Sleep  is  deepest  during  the 
second  hour  after  going  to 
sleep,  and  a  greater  shock  is 
given  to  the  nervous  system 
by  waking  a  sleeper  during 
that  hour  than  at  another 
time.  An  alarm  clock  is 


FIG.    Iy.- 


ON 


A,  resting  cell,  B,  fatigued  cell,  with  its  body    Infants     sleep     most    of     the 
and  nucleus  shrunken.  ^^    and     -<.    ^     injurioUS    tO 

awaken  them.  Adults  usually  require  about  eight  hours 
of  sleep.  There  is  a  risk  in  going  to  sleep  in  a  warm 
room,  for  the  bed  covering  which  is  comfortable  then  may 
not  be  enough  to  prevent  taking  cold  when  the  fire  goes 
out.  Sleep  comes  more  promptly  to  one  who  goes  to 
bed  at  the  same  hour  each  night.  The  muscles  are  re- 


THE  NERVOUS  SYSTEM  203 

J» 

laxed  in  sleep,  and  to  relax  them  perfectly  upon  lying 
down,  tends  to  bring  sleep.  One  who  is  sleepless,  usually 
finds  that  he  is  holding  the  head  stiff  on  the  shoulders,  the 
teeth  clinched,  and  the  muscles  contracted,  even  though 
he  is  lying  down.  Excitement  and  worry  during  the  day, 
but  especially  just  before  retiring,  tend  to  produce  sleep- 
lessness. 

Preparing  for  Severe  Mental  Effort.  —  Two  students  were 
studying  hard  one  night  for  an  examination  to  be  next  day. 
One  of  them  went  to  bed  a  little  earlier  than  usual  as  a  part 
of  his  preparation  for  the  work.  The  other  sat  up  two 
hours  later  than  usual.  The  first  student  made  a  high 
grade ;  the  second  hardly  passed.  To  rest  the  brain  by 
plenty  of  sound  sleep,  and  go  to  work  with  the  brain  cells 
fresh  and  the  blood  pure,  is  a  far  better  preparation  for  an 
examination  than  to  attempt  to  cram  a  few  more  facts  into 
the  head  and  shorten  the  hours  of  sleep.  Loss  of  sleep  is 
a  serious  matter  in  youth  when  the  cells  are  growing. 

Resting  the  Mind  while  Awake.  —  It  is  not  necessary  to 
go  to  sleep  to  rest  the  mind.  Change  of  occupation  and 
change  of  the  subject  of  thought  rest  the  mind  by  resting 
the  tired  nerve  cells  and  bringing  new  cells  into  action. 
Pupils  can  become  rested  more  quickly  by  rising  in  their 
places  and  taking  gymnastic  exercises  than  by  simply 
closing  their  books  and  sitting  still.  Enjoyable  recreation, 
and  doing  things  simply  because  we  like  to  do  them,  are 
very  necessary  to  the  health  of  the  nervous  system  and  to 
success  in  life.  There  are  times  wJicn  change  from  mental 
to  physical  occupation  cannot  bring  rest ;  the  will  power  is 
tired  out,  and  only  ceasing  from  all  activity  will  refresh  us. 

Habits.  —  Our  habits  of  doing  and  thinking  and  feeling 
really  constitute  our  characters.  This  shows  the  importance 
of  right  habits.  By  gradually  changing  our  habits  we  can 


2O4  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

strengthen  our  characters  and  form  them  somewhat  as  we 
wish.  When  a  muscle  contracts  in  a  certain  way,  this  act 
makes  it  easier  for  the  muscle  to  contract  in  that  way  the 
next  time ;  thus  great  muscular  strength  may  be  developed. 
Whenever  a  nerve  cell  acts  in  a  certain  way,  it  is  easier  for 
it  to  act  in  the  same  way  the  next  time. 

How  Habits  are  Changed.  —  We  cannot  all  at  once  change 
our  characters  or  habits  of  thinking  and  feeling  by  mere 
power  of  will.  New  habits  must  be  gradually  formed.  If 
the  cells  used  in  a  certain  deed  or  thought  are  repeatedly 
active,  it  is  believed  that  the  circulation  around  these  cells 
will  be  increased  and  they  will  grow  larger ;  and  the  branches 
that  connect  them  with  other  cells  will  develop  more  and 
more.  Thus  a  good  habit  becomes  fixed,  and  thus  a  bad 
habit  is  formed.  To  overcome  the  bad  habit,  these  cells 
must  be  weakened  by  disuse.  The  branches  that  make  the 
undesirable  connections  with  the  cells  must  be  allowed  to 
draw  back  and  the  blood  supply  to  become  less.  The 
longer  the  cells  are  kept  inactive,  the  less  likely  the  habit 
will  be  to  return ;  but  a  slight  danger  of  its  return  may 
exist  all  during  life.  Habits  that  are  formed  in  youth 
while  the  nervous  system  is  developing  are  the  hardest  to 
break.  It  is  difficult  to  break  a  habit,  whether  good  or 
bad,  that  continues  until  one  is  twenty-five  or  thirty  years 
of  age. 

Education  of  the  Nervous  System.  —  There  is  a  natural 
tendency  to  fall  into  habits,  for  the  body  works  easier  in 
that  way.  There  is  no  reason  for  always  putting  on  one 
shoe  before  the  other,  yet  many  persons  always  put  on 
the  same  shoe  first.  It  is  the  duty  of  every  person,  and 
especially  of  young  people  whose  habits  are  so  easily 
formed,  to  practice  doing  useful  things  well,  such  as 
writing,  speaking,  standing,  walking,  until  the  habit  of  doing 


THE  NERVOUS  SYSTEM 


205 


them  well  becomes  reflex  action  and  the  cerebrum  can  in- 
trust the  action  to  the  lower  nerve  centers.  The  chief  pur- 
pose of  education  is  to  train  children  into  desirable  habits 
of  thinking  and  doing,  so  that  when  they  are  grown  they 
will  have  good  habits  as  good  friends  to  help  them.  We 
cannot  get  entirely  rid  of  our  habits,  because  we  cannot  get 


Great  fissure 


Great  fissure 


FIG.  158.  —  SECTION  ACROSS  CEREBRUM,  showing  thickness  of  gray  matter,  depth 
of  convolutions,  band  of  white  fibers  (i,  5)  connecting  the  two  hemispheres ; 
ventricles  (2)  or  cavities  in  brain. 

rid  of  our  brains.  Self-control,  neatness  in  dress,  slow 
eating,  consideration  for  the  feelings  of  others,  keeping 
the  temper,  mental  and  physical  industry,  are  a  few  things 
that  may  become  habitual  and  help  to  form  the  true  lady 
or  gentleman,  and  make  life  successful  and  happy.  It  is 
usually  easy  to  tell  if  a  person,  as  we  say,  "  has  had  good 
breeding,"  that  is,  has  grown  up  among  people  of  refined 


2O6  L£SSONS  IN  HYGIENIC  PHYSIOLOGY 

habits.  But  no  one  can  set  limits  to  the  power  of  thought 
and  of  confidence  in  one's  self  to  change  nerve  structure. 

Healthy  fatigue  is  caused  by  the  accumulation  of  waste 
products  resulting  from  the  activities  of  the  nerves,  muscles, 
and  other  organs.  Their  presence  in  the  tissues  affects 
the  nerves.  We  feel  rested  when  these  wastes  are  re- 
moved ;  we  are  strong  again  when  the  tissues  are  supplied 
with  fresh  food  and  oxygen.  Work  causes  the  accumulation 
of  carbon  dioxid,  which  is  nature's  narcotic.  The  drowsy 
feeling  that  ensues  is  more  pleasant  than  the  drowsy  feel- 
ing from  alcohol,  or  opium. 

Fatigue  without  work  occurs  with  people  who  are  idle 
and  exert  no  energy,  yet  who  eat  immoderately,  and  perhaps 
live  in  unventilated  houses.  The  oxidation  in  their  cells  is 
not  complete,  and  poisonous  products  of  the  incomplete 
burning  result.  These  are  taken  by  the  blood  to  the  nerves 
and  brain,  and  give  a  tired  feeling  as  effectually  as  does  hard 
work.  Persons  who  do  no  muscular  work  often  have  imper- 
fect digestion  ;  the  food  ferments  in  the  food  tube  and  forms 
poisons  which  increase  the  tired  feeling.  Persons  who  never 
work,  yet  who  never  have  any  energy  and  are  said  to  have 
been  "  born  tired,"  are  suffering  from  this  kind  of  fatigue. 
They  are  usually  irritable,  while  persons  who  are  fatigued 
by  useful  labor  are  likely  to  be  dull  and  drowsy. 

Pains  and  Aches.  —  Pain  is  the  warning  to  the  mind  of  an 
injury  or  a  threatened  injury  to  a  nerve.  As  the  nerves  are 
found  everywhere  except  in  the  epidermis,  hair,  and  nails, 
the  body  is  thoroughly  protected  by  the  nerves.  A  pain  is 
short  and  from  one  spot ;  a  pain  continued  for  a  long  time, 
and  coming  from  a  larger  area,  is  called  an  ache  Pains 
and  aches  may  result  from :  (i)  cutting  or  tearing  a  nerve ; 
(2) pressing  upon  a  nerve  or  stretching  it;  (3)  depriving  a 
nerve  of  nourishment;  (4)  allowing  poison  to  reach  the 


THE  NERVOUS  SYSTEM  2O? 

nerves.  When  the  injury  to  the  nerve  is  located  outside 
of  the  skull,  the  mind  refers  the  pain  to  the  injured  spot. 
When  we  were  infants  we  learned  to  refer  hurts  to  the 
injured  place  on  the  body.  All  our  lives  since  then,  when 
the  pain  comes  along  any  certain  nerve,  we  have  thought 
of  the  cause  of  the  pain  as  being  at  the  end  of  that  nerve. 
Hence  for  many  years  after  an  arm  is  cut  off  irritation  at 
the  end  of  the  stump  causes  an  imaginary  finger  to  itch. 
This  shows  that  the  itching  never  was  in  the  finger,  but 
was  in  the  brain,  even  before  the  finger  was  cut  off.  Pain 
in  the  part  of  the  nervous  system  situated  within  the  skull 
usually  lasts  for  some  time,  and  is  called  a  headache. 
Headaches  may  result  from  either  of  the  four  causes 
of  pain  mentioned  above  except  the  first  (why  not  the 
first  ?),  and  they  will  be  studied  in  the  same  order. 

Headaches  from  excessive  blood  pressure  in  the  brain 
are  caused  by  too  much  blood  in  the  brain.  During  such 
headaches  the  head  may  seem  to  throb  with  each  beat  of 
the  heart.  Excitement  or  momentary  anger  may  bring  on 
this  form  of  headache  by  increasing  the  rate  and  strength 
of  the  heart  beat.  Cold  feet  may  cause  it,  since  the  con- 
tracted capillaries  of  the  feet  prevent  the  usual  amount  of 
blood  from  flowing  through  the  legs  ;  and  the  blood,  which 
cannot  go  downward,  follows  the  arteries  that  lead  up  to  the 
head.  If  a  meal  is  omitted,  the  blood  which  would  have 
gone  to  the  digestive  organs  to  aid  them  in  their  task  may 
accumulate  in  the  head.  If  one's  nerves  are  accustomed 
to  coffee,  tea,  or  wine  taken  at  meals,  leaving  off  a  meal  is 
more  likely  to  cause  a  headache. 

Headaches  from  Imperfect  Nutrition.  —  If  the  blood  in 
the  body  is  thin  or  lacking  in  quantity,  that  is,  if  the  per- 
son is  anemic,  headaches  are  frequent.  (In  what  part  of 
the  head?  See  Fig.  159.)  This  condition  of  the  blood 


2O8  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

(called  a-ne'mi-a)  can  be  cured  by  drinking  plenty  of  water 
and  by  a  more  active  life.  An  active  life  in  the  open  air 
causes  deep  breathing  and  gives  a  good  appetite  and  good 
digestion.  The  air  and  water  and  assimilated  food  soon 
make  plenty  of  pure,  rich  blood,  and  the  headaches  cease. 
What  is  the  color  of  an  anemic  person's  skin  ?  What  does 
this  show  to  be  lacking  in  the  blood  ? 

The  brain  may  be  imperfectly  nourished  because  of  over- 
work. The  headache  is  simply  the  cry  of  a  hungry  nerve 

for  food,  or  for  the  re- 
OiSTWBANces  of  moval  of  carbon  dioxid 
and  other  fatigue  poisons 
(see  next  topic).  Over- 
L-tiEwovsexumsnoN  worked  nerves  result  from 
excessive  mental  labor, 
insufficient  sleep,  worry, 
long-continued  anger,  or 
other  emotional  excite- 
ment. Eye  strain,  a  form 

FIG.  159.— THE  SITUATION  OF  HEADACHES  of  overwork   that   causes 
with  reference  to  their  causes.  many    headacheS)    results 

from  using  the  eyes  upon  fine  work,  or  in  a  poor  light,  or 
in  a  glaring  light,  or  with  light  coming  from  below  the 
level  of  the  eyes.  The  nerves  of  the  eye  may  also  be 
exhausted  from  straining  caused  by  defects  in  the  eye. 
Where  would  this  headache  be?  (Fig.  159.)  Eye  strain 
may  also  exhaust  the  optic  tract  in  the  cerebrum.  Where 
would  such  a  headache  be?  (Fig.  159.) 

Headaches  from  Poisons  and  Impure  Blood.  —  Impurities 
and  poisons  which  cause  headaches,  may  enter  the  body 
from  without,  or  they  may  be  formed  in  the  body.  Ex- 
amples of  poisons  from  without  are,  —  lead  from  lead 
water  pipes,  mercury  in  medicines,  alcoholic  drinks,  car- 


THE  NERVOUS  SYSTEM  209 

bon  dioxid  in  unventilated  rooms,  especially  schoolrooms 
under  the  control  of  careless  teachers.  Coffee,  tea,  and 
tobacco  may  cause  headaches ;  sometimes  by  their  nar- 
cotic or  deadening  effect  they  stop  headaches. 

Among  poisons  formed  within  the  body  and  causing 
headaches  are  carbon  dioxid  and  other  fatigue  poisons. 
Chronic  nasal  catarrh  causes  headaches  because  of  the  im- 
purities thrown  into  the  blood  by  the  breaking  down  of  the 
inflamed  tissues  in  the  nasal  passages.  Food  may  remain 
for  some  hours  undigested  in  the  digestive  organs,  either 
because  it  is  excessive,  indigestible,  or  taken  when  there 
is  no  appetite,  or  when  the  body  is  much  fatigued.  The 
undigested  food  decomposes  in  the  warm,  moist  food  tube, 
and  is  changed  into  poisons  instead  of  nutritious  sub- 
stances. Strange  to  say,  this  does  not  so  often  cause 
stomach  ache  as  headache.  The  reason  for  this  is  that 
the  brain  receives  more  blood  in  proportion  to  its  size 
than  any  other  portion  of  the  body ;  the  poison  circulating 
through  the  brain  often  causes  a  severe  and  painful  trouble 
called  "  sick  headache." 

Prevention  and  Cure  of  Headaches.  —  Headaches,  like  all 
other  pains,  should  be  a  source  of  benefit  in  that  they  show 
us  ways  of  living  to  avoid  in  the  future.  Many  persons, 
however,  not  only  derive  no  profit  from  a  headache,  but 
by  unwise  efforts  to  cure  the  pain,  bring  permanent  injury 
to  themselves  in  addition  to  the  suffering  of  the  headache. 

Bromides,  opium,  and  other  poisons  deaden  and  weaken 
the  nervous  system  while  preventing  the  pressure  or 
poison  that  is  causing  the  headache  from  being  felt. 
Headache  powders,  phenacetin,  acetanelid,  antikamnia,  and 
other  vile  poisons  made  from  coal  tar,  shock  and  weaken 
the  heart  and  reduce  the  vital  activities  so  that  the  head- 
ache is  no  longer  felt.  In  consequence  of  shocks  from 


2IO  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

repeated  doses  of  such  drugs,  the  heart  will  not  work  so 
well,  and  may  give  way  some  time  in  the  future  when  an 
effort  or  strain  makes  unusual  demands  upon  it.  The  liver 
and  kidneys  have  to  destroy  and  remove  the  drugs. 

A  commotion  at  midnight  in  a  hotel  once  disturbed  the 
writer.  He  found  that  a  young  lady  in  the  room  above 
had  been  taking  acetanelid  for  sick  headache ;  her  body 
had  turned  almost  blue  from  the  blood  flow  ceasing,  and 
efforts  were  being  made  to  save  her  life.  She  recovered, 
but  one  week  afterward,  when  another  sick  headache  came 
on  from  overeating  or  exhaustion,  she  at  once  took  the 
same  drug  again.  Many  people  are  foolish  enough  to 
injure  their  bodies  and  risk  death  rather  than  suffer  pain, 
or  avoid  pain  by  prudent  living.  Sick  headaches  are  fore- 
told by  a  dull  feeling,  sleepiness  after  eating,  a  coated 
tongue,  and  constipation.  It  would  be  better  to  remove  the 
undigested,  spoiled  food  from  the  stomach  by  an  emetic 
or  otherwise  than  to  take  a  narcotic.  But  the  most  ra- 
tional way  is,  at  the  first  indication  of  trouble,  to  abstain 
from  eating,  or  use  a  fruit  diet  for  twenty-four  hours,  and 
drink  water  freely.  This  will  enable  the  body  to  dispose 
of  the  excess  of  waste  matter. 

THOUGHT  QUESTIONS  ON  HEADACHES.  —  Write  2,  3,  or  4  after  the 
following  causes  of  headaches  to  show  with  which  of  the  causes  on  page 
206  each  belongs  :  Headache  from"  standing  a  long  written  examination. 
Headache  from  violent  running.  Headache  of  a  drunkard  recovering 
from  a  "spree."  Headache  from  idle  living  and  neglect  of  exercise. 
Headache  of  a  boy  who  hung  with  his  head  downward  while  acting  on  a 
horizontal  bar.  Why  is  it  possible  to  sleep  off  a  headache  ?  What  are 
the  three  causes  of  headache  over  the  eyes?  (See  Fig.  159.)  What 
causes  headache  above  the  ears  ?  In  the  top  of  the  head  ?  In  the 
temples  ?  In  the  back  of  the  head  ?  What  is  the  cure  for  anemic 
headaches  ?  (p.  100.)  How  may  the  drunkard's  headache  be  avoided  ? 
How  should  headaches  from  overwork  be  avoided  ?  Headaches  from 
eye  strain  may  be  avoided  by  the  use  of  glasses  or  by  sparing  the  eyes. 


THE  NERVOUS  SYSTEM  211 

Many  drugs  act  upon  the  body  by  stimulating  the  ner- 
vous system.  They  are  used  with  the  view  of  restoring 
the  balance  when  the  organs  are  not  working  in  harmony. 
A  sick  person  should  ascertain  whether  or  not  the  trouble 
is  caused  by  wrong  habits  of  living.  This  is  as  important 
as  to  employ  a  physician.  It  is  more  necessary  to  change 
wrong  habits  than  it  is  to  take  drugs. 

Applying  Hygiene  systematically.  —  The  cause  of  ill 
health  should  be  sought  with  system  and  thoroughness, 
applying  the  tests  in  rotation  to  every  function  of  the 
body :  Lungs.  Is  the  air  habitually  breathed  fresh  and 
free  from  dust  ?  Is  the  body  held  up,  and  is  the  chest  or 
waist  cramped  by  clothing?  Mtiscles.  Is  enough  physi- 
cal exertion  made  to  cause  deep  breaths  to  be  drawn  ? 
Food.  Is  it  simple,  digestible,  and  eaten  properly  ?  Drink. 
Is  the  water  pure?  Cleanliness,  Work  and  Rest,  Clothing, 
Ventilation,  and  Mental  State  may  be  inquired  into  until 
the  source  of  trouble  is  found  and  the  cause  of  ill  health 
removed.  To  give  drugs  and  leave  the  cause  of  ill  health 
untouched,  is  to  fail.  There  are  signs  of  coming  weakness 
or  illness  which,  if  heeded  and  the  ways  of  living  improved, 
will  usually  prevent  illness.  Among  these  signs  are  head- 
aches, paleness,  sensitiveness  to  cold,  heavy  feeling  or  pain 
after  meals,  constipation.  Huxley  says  that  young  people 
should  so  learn  physiology  and  so  understand  their  bodies 
that  they  will  heed  the  first  signs  of  nature's  displeasure, 
and  not  wait  for  a  box  on  the  ears. 

Nervous  Children.  —  A  report  on  the  health  of  the 
school  children  in  one  of  our  largest  cities  contains  the 
startling  statement  that  one  third  of  the  children  in  those 
schools  have  some  disorder  of  the  nerves.  Nervousness 
(weakened  control  of  the  nerves)  may  show  itself  by  slug- 
gishness of  mind,  great  irritability  of  temper,  frequent 


212  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

spells  of  the  "blues"  or  by  involuntary  movements  of  a.  jerky 
or  fidgety  kind.  Sound  development  of  city  children's 
nerves  is  hindered  because  of  the  constant  noise  in  cities 
both  day  and  night ;  by  shortening  of  the  hours  of  sleep  ; 
by  excessive  use  of  sugar  for  food  ;  by  living  much  among 
people  with  no  chance  to  be  alone  and  let  the  nerves  rest, 
and  among  boys  by  the  use  of  cigarettes. 

Need  of  Freedom  for  Growing  Children.  —  No  farmer 
thinks  of  confining  or  of  working  a  colt  until  it  is  nearly 
grown  and  its  body  has  reached  a  certain  degree  of  tough- 
ness. Dr.  Seaver  says  that  free  activity  and  opportunity 
for  gratifying  the  instinct  to  play  is  .almost  as  necessary  for 
growing  girls  and  boys  as  it  is  for  a  colt.  Confinement 
for  too  many  hours  in  school,  or  staying  closely  in  the 
house  and  reading  books,  may  stunt  and  weaken  their 
bodies  for  life.  Book  work,  although  useful  and  almost 
as  indispensable  as  health  for  success  in  life,  is  not  a 
natural  occupation  even  for  adult  man.  It  is  unknown 
among  tribes  that  lead  simple  lives.  The  strain  upon  the 
eyes,  $&&  flattening  of  the  chest,  the  breathing  of  indoor  air, 
and  the-  restraint  upon  the  muscles  make  the  study  of 
books  a  risk  to  the  health  of  children  if  injury  is  not 
carefully  guarded  against.  So  slight  is  the  regard  for 
health  by  parents  and  teachers  that  scholarship  is  more 
often  the  first  aim.  The  recent  plan  in  progressive  schools 
of  having  physical  exercises  in  the  midst  of  each  division 
of  the  day's  session  is  not  likely  to  be  given  up.  The 
reason  stated  for  retaining  it  is  not  in  the  improved  bodies 
that  doubtless  result,  but  because  the  relief  from  mental 
strain  enables  the  pupils  to  study  better  after  the  physical 
exercise  is  over.  Statistics  show  that  the  most  successful 
men,  and  even  the  best  scholars  in  the  world  to-day,  do  not 
come  from  schools  where  much  book  work  in  and  out  of 


THE  NERVOUS  SYSTEM  21  j 

school  is  required  for  ten  months  in  the  year,  but  from 
localities  where  the  schools  are  open  not  longer  than  six 
or  eight  months  in  the  year,  and  the  chance  for  stuffing 
the  mind  is  limited.  In  such  districts  the  pupils  often  walk 
miles  to  school,  a  custom  that  would  be  considered  beyond 
the  power  of  city  children. 

How  to  prevent  Confinement  and  Study  from  injuring 
Children.  —  This  is  an  important  question,  for  upon  its 
answer  depends  whether  children  shall  grow  up  weak  and 
nervous,  or  successful  and  efficient  workers,  (i)  Venti- 
lation is  of  first  importance.  The  air  of  many  homes 
and  schoolrooms  is  very  impure.  (2)  The  time  devoted  to 
work  should  not  be  very  long,  especially  in  the  lower 
grades.  (3)  The  work  should  be  diversified ;  not  only 
books,  but  natural  objects  and  the  outdoor  world  should 
be  studied.  The  pupils  should  be  taught  how  to  live 
instead  of  being  trained  into  unhealthy  habits  of  living. 
Wisdom,  or  the  knowledge  how  to  live,  is  as  important  as 
learning,  or  the  knowledge  of  books.  What  is  learned  in 
books  may  be  forgotten  in  a  few  years,  but  the  knowledge 
how  to  live  is  useful  for  the  rest  of  life.  A  child  that  is 
devoted  to  books  so  as  to  study  continually  is  an  abnor- 
mal child.  (4)  The  teacher  and  parent  should  see  that 
the  habitual  poise  of  the  child  is  favorable  to  health  and 
activity,  and  that  the  attitude  assumed  does  not  inter- 
fere with  breathing  and  blood  flow.  A  sensible  child  will 
heartily  cooperate  in  this.  Study  Figs.  49,  59,  61.  (5)  The 
children  should  be  encouraged  to  play,  and  every  possible 
opportunity  should  be  given  to  gratify  the  play  instinct. 
(6)  Physical  exercise  should  be  provided  at  short  intervals, 
especially  stretching  exercises  and  movements  that  straighten 
the  spine  and  hips  and  elevate  the  chest.  Running  games 
at  recess  are  of  the  greatest  value.  Dr.  Seaver  says  that 


2I4 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


children  under  nine  years  of  age  should  be  given  physical 

movements  in  school  for  five  minutes  in  every  half  hour ; 

from  nine  to  thirteen  years,  ten  minutes  every  hour ;  above 

thirteen  years  of  age,  fifteen 
or  twenty  minutes  in  the 
middle  of  both  morning  and 
afternoon  sessions. 

The  effect  of  alcohol  upon 
the  nerves  is  in  rare  cases  to 
bring  on  a  painful  disease 
called  neuritis,  or  inflamma- 
tion of  the  nerves.  (The  end- 
ing "itis"  means  an  inflam-* 

FIG.  i6o.-FouR  CELLS  from  the  brain  nation.     What  is  tonsilitis  ?) 

of  a  man  who  died  of  alcoholic  insanity.  Alcohol  Seems  to  attack  the 
Compare  with  A,  Fig.  142.     A  drunkard  with  v         •         •  «,i 

nerve  cells  partly  destroyed  will  hardly  have    nCrVC  CCntCrS,  beginning  With 
will  power  to  break  a  habit.  ^     cerebrum>     the     highest, 

and  proceeding  toward  the  lowest.  Hence  as  a  man  be- 
comes drunk  he  talks  foolishly  (cerebrum  affected)  before  he 
staggers  (cerebellum  affected),  and  he  finally  goes  to  sleep 
and  breathes  very  hard  (medulla  affected)  in  a  drunken 
stupor.  It  sometimes  happens  that  the  breathing  center 
is  completely  disabled,  and  the  man  dies  from  the  strong 
poison.  For  the  effect  of  chronic  alcoholism  upon  the 
nerve  cells,  see  Fig.  160. 

PRACTICAL  QUESTIONS.  —  1.  Why  does  travel  often  cure  a  sick 
person  when  all  else  fails  ?  2.  Why  is  working  more  healthful  than 
"taking  exercise"?  (p.  62.)  3.  Is  it  better  for  children  to  play  or 
to  take  exercise?  4.  Why  can  one  walk  and  carry  on  a  conversation 
at  the  same  time?  (p.  196.)  5.  How  does  indigestion  cause  a  head- 
ache r  (p.  209.)  6.  Does  perfectly  comfortable  clothing  from  head 
to  foot  help  to  make  one  at  ease  in  company?  Does  uncomfortable 
clothing  tend  to  make  one  awkward?  7.  Why  is  it  as  important  to 
have  the  shoes  and  clothes  perfectly  comfortable  when  going  out  as 
<vt>er»  staying  at  home  ?  8.  When  one's  finger  is  cut,  where  is  the 


THE  NERVOUS  SYSTEM  21$ 

pain?  (p.  207.)  9.  Does  the  girl  who  frets  over  washing  the  dishes, 
working  with  an  unwilling  mind,  and  the  boy  who,  while  he  is  sawing 
wood,  is  wishing  to  go  to  a  baseball  game,  do  their  work  with  more 
or  less  fatigue  than  if  they  worked  cheerfully  and  willingly?  Why? 
10.  In  what  two  ways  may  opening  a  window  when  a  student  is  becom- 
ing dull  and  drowsy  at  his  books  enable  him  to  wake  up  and  study  with 
ease?  (p.  221.)  11.  What  kinds  of  cells  shrivel  like  a  baked  apple 
when  they  become  fatigued  ?  (Fig.  157.)  12.  A  nerve  or  nerve  fiber 
can  hardly  become  tired  or  fatigued,  for  the  nerve  cell  supplies  the 
energy.  What  do  we  mean  when  we  say  the  nerves  are  worn  out? 
(Fig.  157.)  13.  Why  do  you  throw  cold  water  upon  a  fainting  per- 
son? 14.  Why  does  constant,  moderate  drinking  undermine  the 
health  more  than  occasional  intoxication?  15.  Why  does  stoppage 
of  the  circulation  cause  one  to  faint?  (See  Chap.  VI.)  16.  Why  is 
grazing  the  skin  often  more  painful  than  cutting  it?  (Fig.  22.) 
17.  Do  alcohol  and  other  narcotics  first  tear  down  the  tissue  of  the 
higher  or  lower  nerve  centers  ?  18.  Why  do  the  lower  animals  always 
act  upon  sudden  impulse?  What  part  of  the  brain  enables  man  to 
retain  sensations  and  not  act  upon  them  until  later?  19.  Does  "ner- 
vousness" more  clearly  indicate  a  bright  mind  or  a  high  temper? 
20.  What  is  the  effect  of  a  cold  bath  upon  the  nerves? x  (Chap.  II.) 

REVIEW  QUESTIONS  (STIMULANTS  AND  NARCOTICS).  —  What  effect 
does  alcohol  have  upon  one-celled  animals  like  the  ameba?  State  a  fact 
which  shows  that  alcohol  used  as  a  beverage  weakens  the  vitality  of 
the  cells  and  lessens  their  power  to  repair  the  tissues  of  the  body  (p. 
48).  How  does  alcohol  affect  the  capillaries  of  the  skin?  The  mucous 
membrane  of  the  stomach?  Does  alcohol  strengthen  the  heart?  Is  it 
a  heart  stimulant?  How  does  alcohol  affect  lung  tissue?  Is  alcohol  a 
food  ?  What  were  the  facts  shown  by  Atwater's  experiments  ?  What 
was  his  conclusion?  What  facts  were  proven  by  Beebe?  What  is  the 
probable  explanation  of  them  ?  Were  Atwater's  experiments  with  ab- 
stainers?  Were  Beebe's?  Why  do  experiments  upon  total  abstainers 
give  slightly  different  results  from  experiments  upon  drinkers?  What 
disease  of  the  nerves  is  sometimes  caused  by  alcohol?  In  what  order 
are  the  nerve  centers  disabled  by  alcohol  ?  State  the  two  reasons  why 
cigarettes  are  far  more  destructive  to  health  than  cigars. 

1  A  shower  bath  is  best  to  stimulate  the  nerves  in  the  skin.  If  a  bath  room 
is  not  at  hand,  it  may  be  taken  by  tacking  one  yard  of  oil  cloth  upon  a  wooden 
frame  and  using  it  for  a  mat  upon  which  the  bather  stands  and  pours  water 
upon  himself  with  a  pitcher  or  flower  sprinkler.  A  hath  mat  and  sponge  are 
preferable  to  a  tub,  as  only  fresh  water  reaches  the  body.  An  air  bath  of  half 
an  hour  with  vigorous  rubbing  is  good  for  the  nerves. 


2l6  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

Definitions :  Stimulant,  Narcotic,  Poison.  —  A  stimulant 
is  anything  that  causes  the  body  to  do  more  work  without 
giving  extra  strength  with  which  to  do  it. 

A  narcotic  is  anything  that  deadens  or  dulls  the  nervous 
system.  It  comes  from  a  word  meaning  "  to  benumb." 

Poisons  are  active  substances  which,  taken  in  quantities 
as  man  takes  food,  destroy  life ;  in  smaller  quantities  they 
injure  the  body  and  may  destroy  life.  Alcohol  is  a  poison. 
Wine,  beer,  whisky,  contain  varying  quantities  of  it. 

The  Narcotic  and  Stimulant  Effects  of  Poisons.  —  Ex- 
amples of  poisons  are  alcohol,  nicotin,  opium,  arsenic, 
strychnin.  Poisons  excite  the  body  when  taken  in  small 
doses,  while  in  large  doses  they  produce  paralysis  and 
death.  The  exciting  or  stimulating  effect  is  due  to  derange- 
ment of  the  functions  or  to  the  efforts  of  the  cells  to  free 
the  body  of  the  destructive  substance.  The  narcotic  effect 
is  due  to  the  poison  having  so  benumbed  the  nerves  and 
injured  the  cells  that  their  activities  cease,  or  become  less 
for  a  time.  You  readily  see  how  the  same  poison  can  be 
both  a  stimulant  and  a  narcotic :  the  stimulating  effect 
always  comes  first,  folloived  by  the  stupefying-  effect.  If  the 
dose  is  very  small,  the  stimulating  effect  will  last  longer ; 
if  it  is  large,  the  narcotic  effect  is  greater  and  felt  more 
quickly. 

Reaction.  —  This  is  the  depressed  and  exhausted  condi- 
tion that  comes  on  after  a  period  of  unnatural  activity.  It 
follows  the  exciting  effects  of  even  those  stimulants  which 
are  not  narcotics.  The  exhaustion  that  follows  the  first 
exciting  effect  of  narcotics  helps  the  narcotic  in  further 
depressing  the  activity  of  the  body. 

Natural  Stimulants.  —  If  there  were  nothing  to  arouse 
activity,  life  would  be  impossible.  A  cold  wind  is  a  stimu- 
lant, since  it  arouses  energy  but  gives  none.  The  activity 


THE  NERVOUS  SYSTEM  21J 

aroused  by  a  cold  wind  is  just  enough  to  help  the  body  with- 
stand the  cold ;  artificial  stimulants  cause  an  expenditure 
having  no  relation  to  the  needs  of  the  body.  Hence  there  is 
a  great  waste  of  energy.  Feelings  may  stimulate,  as  love 
for  his  family  may  stimulate,  a  man  to  labor.  The  desire 
for  knowledge  may  stimulate  a  boy  to  study.  Hunger  may 
stimulate  a  man  to  eat.  Hunger  is  a  natural  stimulant, 
and  is  not  likely  to  make  him  eat  to  excess ;  tea,  coffee, 
pepper,  etc.,  arouse  a  false  appetite.  These  things  are  used 
chiefly  for  their  stimulant  effect,  since  they  contain  little  or 
no  nourishment.  The  rest  of  this  chapter  treats  of  arti- 
ficial stimulants.  Such  stimulants  always  cause  an  unregu- 
lated and  unhcaltJiy  action,  and  are  always  followed  by 
reaction. 

How  Much  Strength  is  stored  in  the  Body  ?  —  Dr.  Tanner 
of  Minnesota  believed  that  most  people  eat  too  much. 
Another  physician  said  that  no  human  being  could  go  forty 
days  without  food.  Dr.  Tanner  made  the  experiment. 
He  lost  thirty-six  pounds  in  weight,  but  he  weighed  12 \\ 
pounds  and  had  considerable  strength  at  the  end  of  the 
forty  days.  The  first  thing  he  ate  at  the  close  of  his  fast 
was  the  juice  of  a  ripe  watermelon. 

Once  some  miners  were  shut  in  by  the  caving  of  a  part 
of  a  mine.  But,  unlike  the  case  just  described,  they  were 
without  water  as  well  as  food.  When,  by  digging,  the 
rescuers  reached  them  seven  days  after,  several  were  still 
found  alive,  although  most  of  them  had  died.  The  miners, 
no  doubt,  had  nourishment  in  their  bodies  for  some  weeks 
more  of  life,  but  the  body  lacked  water  to  dissolve  it  and 
bring  it  within  the  reach  of  the  cells  most  needing  it. 

A  Stupendous  Fact.  —  These  incidents  show  how  wisely 
the  body  is  made,  and  prove  that  the  cells  store  up  nourish- 
ment for  weeks  ahead.  The  large  amount  of  nourishment 


218  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

stored  in  the  human  body  is  one  of  the  most  striking  and 
important  facts  with  which  the  science  of  physiology  has 
to  deal,  and  it  should  be  borne  in  mind,  or  we  may  make 
great  mistakes  about  some  very  simple  matters. 

Foolish  Rashness.  —  Did  you  ever  get  so  tired  that  you 
had  to  give  up  and  stop,  however  much  you  would  have 
liked  to  continue  at  work  or  play  ?  To  rest  was  the  wise 
thing  to  do.  Because  you  have  now  learned  from  physiology 
how  much  energy  you  have  stored  up  within  your  frame, 
you  should  not  in  the  future  be  tempted  to  go  on  until  you 
almost  break  down.  Probably  you  know  people  who  are 
conceited  about  their  bodies  and  say  they  are  "  made  of  cast 
iron  "  ;  that  nothing  can  hurt  them.  Did  you  ever  know 
anybody  who  was  conceited  about  his  mind  and  thought 
he  was  very  bright?  It  is  just  as  foolish  to  be  conceited 
about  the  body  as  about  the  mind. 

How  a  Safeguard  may  be  broken  down.  —  It  is  a  very 
wise  arrangement  that,  under  ordinary  conditions,  we  can- 
not get  at  the  surplus  energy  we  have.  Carbon  dioxid  and 
other  wastes  accumulate  in  the  tissues  and  paralyze  the 
nerves.  Fatigue  and  other  feelings  compel  us  to  be  provi- 
dent, as  it  were ;  yet  stimulants  and  narcotics,  by  irritating 
the  nerve  cells,  arouse  them  and  cause  us  to  expend  some 
of  this  reserve  energy.  Thus  man  is  enabled  to  get  at 
this  precious  store  which  he  should  save  for  emergencies, 
when  he  is  sick  and  cannot  digest  food,  or  when  he  is 
making  some  mighty  effort.  This  reserve  energy  may  be 
needed  to  enable  him  to  pass  through  some  very  trying 
time  without  breaking  down.  Did  you  ever  know  of  a 
weak,  sick  person  who  had  eaten  very  little  for  weeks,  yet 
was  so  powerful  that  it  took  several  strong  men  to  hold 
him  in  bed  ?  This  sometimes  happens  in  the  case  of  a 
sick  person  who  is  delirious  and  crazed  by  pain  and  by  the 


THE  NERVOUS  SYSTEM  2IQ 

poisons  formed  in  the  body  during  illness.  But  the  deliri- 
ous mania  often  uses  up  the  little  energy  left,  and  costs 
the  person  his  life. 

The  only  source  of  energy  for  man's  body  is  the  union 
of  food  and  oxygen;  he  must  get  his  energy  from  the 
same  source  that  the  engine  does ;  and  this  is  from  his 
food,  which  serves  as  fuel,  and  the  oxygen  which  burns  it. 

Fatigue  of  Body  and  Brain.  —  Suppose  you  are  tired  or 
worked  down.  The  fatigue  depresses  you  and  you  feel 
discouraged.  What  ought  you  to  do?  Why,  rest,  of 
course,  and  you  will  soon  feel  all  right  again.  This  seems 
very  simple,  yet  some  people  will  not  do  this  way,  but  will 
take  an  alcoholic  beverage  or  tobacco,  which  will  keep 
them  from  feeling  tired  when  they  are  tired.  If  you  have 
been  working  hard  preparing  for  examinations,  or  gather- 
ing hay,  or  in  attending  to  some  important  business,  or 
have  been  under  the  excitement  of  some  pleasure  trip,  and 
feel  "  blue  "  and  worn  out,  then  bear  the  result  like  a  man, 
or  like  a  true  boy  or  girl,  as  the  case  may  be.  Giving  up 
for  a  while,  or  "toughing  it  out"  with  the  blues,  or  losing 
a  little  time  from  business,  will  not  hurt  you,  but  will  make 
you  strong,  while  a  stimulant  will  leave  you  less  of  a  man 
than  before. 

Alcohol  is  used  to  get  strength  out  of  a  man,  not  to  put 
it  in.  W7hen  a  person  feels  that  he  is  all  tired  out  and  his 
nerves  are  weak  and  takes  a  stimulant,  it  is  the  same  as  if, 
when  his  horse  shows  signs  of  breaking  down,  he  should 
lash  him  with  a  keen  whip,  or  pierce  him  with  a  sharp 
spur,  instead  of  letting  him  rest.  Many  a  fine  horse  has 
been  spoiled  in  a  few  hours  under  the  sting  of  the  whip, 
and  many  a  man  has  been  physically  ruined  for  life  by 
overworking,  goaded  on  by  alcohol,  during  one  season  of 
business  rush. 


22O  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

Mistaking  the  Source  of  Energy.  —  You  remember  those 
wonderful  little  one-celled  animals,  the  amebae.  If  poison 
is  brought  near,  they  will  try  to  escape  it.  Likewise,  if  a 
man  who  has  never  used  either  alcohol  or  tobacco,  takes 
one  of  them  into  his  body,  the  cells  will  try  to  throw  it  off. 
Secretions  are  poured  out  by  the  cells  to  dilute  and  weaken 
the  poison,  and  the  derangement  of  the  organs  excites  the 
body  to  some  extent.  This,  with  the  dulling  effect  upon  the 
nerves,  keeps  the  man  from  noticing  fatigue  ;  so  he  thinks 
the  narcotic  has  given  him  renewed  strength.  Strychnin 
is  one  of  the  deadliest  poisons  known,  and  also  one  of  the 
most  powerful  stimulants.  If  a  cat  is  given  strychnin, 
its  nerve  tissue  becomes  so  irritable  that  a  loud  sound,  or 
merely  touching  any  part  of  the  animal  will  throw  every 
muscle  of  its  body  into  a  spasm. 

Quieting  the  Nerves.  —  Some  people  are  coffee  topers 
and  tea  topers.  It  is  a  mistake  to  say  these  things  quiet 
the  nerves.  Who  is  so  nervous  as  the  old  lady  who  drinks 
frequent  cups  of  tea  to  quiet  her  nerves?  It  is  the  tea 
that  is  making  her  nerves  unsteady.  Some  people  unac- 
customed to  tea  will  lie  awake  the  greater  part  of  the 
night  wearing  out  their  energies  by  sleeplessness  if  they 
drink  only  one  cup  of  it.  Useful  labor,  pleasant  games, 
and  a  contented  mind  will  quiet  the  nerves  without  injur- 
ing them. 

Stimulants  have  less  medicinal  effect  when  given  to 
persons  already  accustomed  to  their  use.  It  is  easy  to 
understand  how  a  person  sitting  up  with  a  friend  who  is 
dangerously  ill  will  take  tea  or  coffee  to  keep  him  wide 
awake,  If  he  is  not  in  the  habit  of  using  them,  they  will 
keep  him  awake  more  effectively  than  if  his  body  has 
become  used  to  such  an  unnatural  intruder.  In  some 
emergencies  there  may  possibly  be  reason  in  stimulating 


THE  NERVOUS  SYSTEM  221 

the  activities,  even  if  reaction  and  depression  must  be 
suffered  thereafter.  One  whose  strength  has  given  out 
because  of  exposure  to  severe  weather  may  be  temporarily 
revived  by  alcohol.  //  will  not  be  wise  to  do  so  unless  it 
is  certain  that  a  warm  fire  and  protection  will  be  reached 
before  the  reaction  comes.  Much  less  would  be  necessary 
to  revive  an  abstainer  than  a  drunkard.  But  is  it  unwise 
habitually  to  disturb  the  body  with  narcotics,  such  as  alco- 
hol or  tobacco  ? 

Natural  stimulants  do  not  cause  depression.  The  chief 
natural  stimulants  are  cold  air,  sunlight,  pure  air,  physical 
exercise,  interest,  joy,  and  other  emotions.  A  deep  breath 
of  pure  air  is  a  better  stimulus  than  a  glass  of  beer ;  climb- 
ing a  hill  or  sawing  a  log  of  wood  will  make  the  blood  flow 
faster  than  will  alcohol;  a  pleasant  talk  with  a  friend  is  a 
better  sedative  than  a  cigar;  a  cold  day  will  steady  the 
nerves  better  than  an  opiate ;  a  trust  that  a  good  Power 
rules  over  all  will  drive  away  worry  quicker  than  cocaine ; 
a  cold  bath  will  bring  steadier  nerves  than  coffee ;  a  cold 
wind  will  give  a  better  appetite  than  food  soured  with 
vinegar  or  hot  with  pepper.  Natural  stimulants  do  not 
produce  a  reaction  because  they  do  not  excite  the  body  to 
an  injurious  degree,  nor  cause  the  energies  to  be  consumed 
beyond  the  danger  point.  Persons  who  go  through  life 
under  the  stimulus  of  these  natural  blessings  have  sound, 
steady  nerves  and  clear  brains.  They  do  not  have  to  take 
anything  to  "  quiet  their  nerves." 

Artificial  Stimulants.  —  Suppose  man  wishes  to  improve 
on  the  simple  blessings  of  life.  He  must  stay  in  the 
house  continually  in  order  to  transact  much  business  and 
make  money,  or  to  acquire  precious  wisdom  in  musty 
books.  He  must  curtain  off  the  sunshine  for  fear  it  will 
cause  his  fineries  to  fade,  must  shut  out  the  air  and  keen 


222  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

in  the  dust.  He  fears  a  cool  draft  upon  a  skin  made 
delicate  by  a  load  of  clothing  or  overheated  rooms.  The 
motions  of  his  body  are  confined  mostly  to  his  fingers 
and  his  tongue  as  he  writes  and  talks  in  transacting  busi- 
ness ;  he  is  too  proud  to  walk  or  to  work  with  his  hands, 
and  thus  the  circulation  throughout  his  body  becomes  slug- 
gish. His  natural  appetite  becomes  weak,  and  would 
regulate  the  amount  of  food  according  to  the  narrow,  one- 
sided life  he  is  living,  but  he  arouses  an  artificial  one  with 
sour  or  peppery  seasonings,  and  the  half-digested  food 
makes  poison  for  his  blood.  His  nerves  become  weak, 
his  mind  weary,  his  body  tired  and  depressed. 

The  Apparent  Result.  —  He  adopts  the  use  of  poisonous 
stimulants,  for  in  the  effort  to  rid  themselves  of  the  poisons 
the  cells  become  active,  and  the  awakening  of  his  weak- 
ened system  gives  him  the  feeling  of  power  and  enables 
him  to  stick  to  his  work  and  his  unhealthy  life.  Coffee, 
tea,  tobacco,  wine,  beer,  whisky,  form  the  steps  toward 
ruin.  He  may  feel  worn  out,  but  a  strong  cigar,  sending 
the  poisonous  fumes  of  nicotin  into  his  delicate,  thin- 
walled  lungs,  will  so  excite  his  nerves  that  he  feels 
vigorous,  and  says,  "What  nerve  strength  comes  from 
tobacco !  "  For  we  feel  vigorous  when  we  are  expending 
energy  very  rapidly,  even  if  the  store  of  energy  is  nearly 
exhausted.  He  feels  discouraged  and  weak,  and  takes 
a  glass  of  whisky :  this  disturbance  to  the  system,  with 
the  great  amount  of  energy  expended  in  getting  rid  of 
it,  makes  him  think  he  has  had  a  sudden  increase  of 
strength. 

Old  Friends  Forgotten.  —  He  forgets  the  work  that  the 
faithful,  industrious  stomach  has  been  doing  in  storing 
away  food  in  the  cells  (alcohol  is  never  stored  in  the 
cells,  but  all  foods  are).  He  forgets  the  busy  lungs  and 


THE  NERVOUS  SYSTEM  223 

the  oxygen  they  have  been  storing  in  the  blood.  He 
knows  nothing  of  the  millions  of  little  cells  that  have 
been  storing  up  food  in  the  tissues  ready  for  use. 

The  Real  Result.  —  The  drinker  is  like  the  man  who 
has  piled  up  money  in  a  bank  and  draws  it  out  with 
checks  and  says :  "  What  a  wonderful  thing  a  check  is ! 
How  valuable  is  my  check  book ! "  But,  if  he  were  to 
lose  the  check  book,  the  bank  would  give  him  another 
for  nothing.  The  check,  when  written,  is  a  sign  that 
money  must  come  out  of  the  bank,  and  the  alcohol, 
when  taken  into  the  body,  is  a  sign  that  strength  must 
come  out  of  the  body  in  destroying  the  enemy.  No 
wonder  the  man  has  a  bad  headache  the  next  morning; 
no  wonder  his  health  and  character  are  gradually  ruined. 

Two  Kinds  of  Thriftlessness.  —  Did  you  ever  know 
persons  who  could  not  keep  any  money  or  property  ? 
Dollars  seem  to  burn  holes  in  their  pockets.  They 
do  not  know  how  to  economize  when  resources  are  low, 
but  are  always  getting  in  debt  and  borrowing,  and 
mortgaging  their  crops  or  their  stock  or  their  homes. 
There  are  many  such  people,  and  there  are  just  as 
many  who  cannot  store  up  any  of  that  precious  capital 
consisting  of  bodily  health  and  strength.  If  they  feel 
buoyant  and  strong,  they  will  not  economize  their 
strength,  but  work  or  go  on  until  they  are  worn  out, 
and  then  take  tobacco  or  alcohol  to  deaden  the  tired 
feeling.  If  a  man  is  weary,  it  is  not  to  his  interest  to 
feel  rested  until  he  is  rested.  Such  feelings  are  a 
cheating  of  nature. 

President  of  N.  Y.  Central  R.R.  on  the  Effects  of  Tobacco 
and  Alcohol.  —  It  was  reported  that  Mr.  Depew  had 
become  a  believer  in  tobacco  and  had  bought  cigars  and 
smoked  with  some  friends  at  the  Mills  Hotel,  New  York. 


224  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

This  is  his  reply  to  a  lady  who  inquired  if  the  report  was 
true :  — 

"NEW  YORK  CENTRAL  &  HUDSON  RIVER  R.R.  Co. 

NEW  YORK,  Jan.  27,  1898. 
"  OFFICE  OF  PRESIDENT. 

"Miss  LUCY  PAGE  G ASTON, 

"  Dear  Madam :  I  am  in  receipt  of  your  letter  of  Jan.  2oth. 
"  I  did  not  buy  any  cigars  at  the  Mills  Hotel  and  have  not  smoked 
one  for  many  years.     The  statement  in  your  slip  (herewith  returned) 
about  my  abandoning  the  habit  is  entirely  correct. 

"  Yours  very  truly, 

"CHAUNCEY  M.  DEPEW." 

The  following  is  the  slip  referred  to,  giving  his  experience 
as  a  smoker:  — 

"  I  used  to  smoke  twenty  cigars  a  day,  and  continued  it  until  I  be- 
came worn  out.  I  didn't  know  what  was  the  matter  with  me,  and  the 
physicians  that  I  applied  to  did  not  mention  tobacco.  I  used  to  go  to 
bed  at  two  o'clock  in  the  morning  and  wake  at  five  or  six.  I  had  no 
appetite  and  was  a  dyspeptic. 

"  I  was  in  the  habit  of  smoking  at  my  desk  and  thought  that  I  derived 
material  assistance  in  my  work  from  it.  After  a  time  I  found  that  I 
couldn't  do  any  work  without  tobacco.  I  could  not  prepare  a  brief  or 
argument  without  tobacco,  but  still  1  was  harassed  by  feeling  that  some- 
thing was  amiss,  and  the  result  was  not  up  to  the  mark. 

"  I  also  found  that  I  was  incapable  of  doing  any  great  amount  of 
work.  My  power  of  concentration  was  greatly  weakened,  and  I  could 
not  think  well  without  a  lighted  cigar  in  my  mouth.  Now  it  is  per- 
fectly clear  that  without  this  power  of  concentration  a  man  is  incapable 
of  doing  many  things.  It  is  this  which  enables  him  to  attend  to  vari- 
ous affairs ;  to  drop  one  absolutely  and  take  up  another  and  give  it  full 
attention.  One  day  I  bought  a  cigar  and  was  puffing  it  with  a  feeling 
of  pleasure  which  is  only  possible  to  the  devotee.  I  smoked  only  a  few 
moments,  and  then  took  it  out  of  my  mouth  and  looked  at  it.  I  said  to 
it :  *  My  friend  and  bosom  companion,  you  have  always  been  dearer  to 
me  far  than  gold.  To  you  I  have  ever  been  devoted,  yet  you  are  the 
cause  of  all  my  ills.  You  have  played  me  false.  The  time  has  come 
that  we  must  part.'  I  gazed  sadly  and  longingly  at  the  cigar,  then 
threw  it  into  the  street.  I  had  been  convinced  that  tobacco  was  ruin- 
ing me. 


THE  NERVOUS  SYSTEM  22$ 

"  For  three  months  thereafter  I  underwent  the  most  awful  agony.  I 
never  expect  to  suffer  more  in  this  world  or  the  next.  I  didn't  go  to 
any  physician  or  endeavor  in  any  way  to  palliate  my  sufferings.  Pos- 
sibly a  physician  might  have  given  me  something  to  soften  the  tortures. 
Neither  did  I  break  my  vow.  I  had  made  up  my  mind  that  I  must  for- 
ever abandon  tobacco,  or  I  would  be  ruined  by  it. 

"  I  have  never  smoked  from  that  day  to  this  ;  and,  while  no  one  knows 
better  than  I  the  pleasures  to  be  derived  from  tobacco,  I  am  still  well 
content  to  forget  them,  knowing  their  effect." 

The  following  remarks  on  the  effects  of  alcohol  are  from 
a  speech  by  the  same  observer :  — 

"  Twenty-five  years  ago  I  knew  every  man,  woman,  and  child  in  Peeks- 
kill,  and  it  has  been  a  study  with  me  to  mark  boys  who  started  in  every 
grade  of  life  with  myself  to  see  what  has  become  of  them.     I  was  up 
last  fall  and  began  to  count  them  over.     It  was  an  instructive  exhibit 
Some  of  them  became  clerks,  merchants,  manufacturers,  lawyers,  doctors. 

"  It  is  remarkable  that  every  one  of  those  that  drank  is  dead ;  not 
one  living  of  my  age.  Barring  a  few  who  were  taken  off  by  sickness, 
every  one  who  proved  a  wreck  and  wrecked  his  family  did  it  from  rum 
and  no  other  cause. 

"  Of  those  who  were  church-going  people,  who  were  steady,  industri- 
ous, and  hard-working  men,  who  were  frugal  and  thrifty,  every  single 
one  of  them,  without  an  exception,  owns  the  house  in  which  he  lives 
and  has  something  laid  by,  the  interest  on  which,  with  his  house,  would 
carry  him  through  many  a  rainy  day." 

The  use  of  alcohol  is  a  great  disadvantage  in  business. 
Would  you  prefer  an  abstainer  or  a  drinking  man  for  a 
physician,  for  the  engineer  of  the  train  you  travel  on,  for 
a  teacher?  The  following  notices  show  the  effect  of 
drinking  alcohol  upon  a  railway  man's  success :  — 

"CANADIAN  PACIFIC  RAILWAY  COMPANY. 

"  In  the  interests  of  safety  and  efficiency,  the  use  of  intoxicants  while 
on  duty  is  absolutely  prohibited.  No  instance  of  intoxication  on  duty 
will  ever  be  overlooked,  but  will  be  followed  by  immediate  dismissal. 
The  habitual  use  of  intoxicating  liquors  will  be  considered  sufficient 
cause  for  dismissal,  and  preference  will  in  every  case  be  given  to  those 
who  abstain  from  their  use. 

"J.  W.  LEONARD,  General  Superintendent^ 
o 


226  L£S30NS  IN  HYGIENIC  PHYSIOLOGY 

"NEW  YORK  CENTRAL  &  HUDSON  RIVER  R.R.  Co. 

•'The  use  of  intoxicating  drink  on  the  road  or  about  the  premises  of 
the  corporation  is  strictly  forbidden.  No  one  will  be  employed,  or  con- 
tinued in  employment,  who  is  known  to  be  in  the  habit  of  drinking 
intoxicating  liquor. 

"E.  VAN  ETTEN,  General  Superintendent." 

Is  the  Moderate  Use  of  Alcohol  by  a  Nation  possible  ?  — 
In  America,  those  who  use  alcohol  often  refer  to  Ger- 
many and  other  European  countries  where  they  suppose 
the  people  have  found  it  possible  to  use  alcohol  without 
going  to  excess.  Professor  J.  H.  W.  Stuckenberg,  of 
Harvard  University,  has  translated  most  of  the  following 
statements  by  Germans : * 

PRINCE  BISMARCK  :  "  Beer  makes  people  stupid,  lazy,  and  inca- 
pable." (23ier  mocfyt  bitmm,  foul,  unb  impotent) 

PROFESSOR  HELMHOLTZ  :  "  Beer  instantly  dispels  my  best  ideas." 

G.  ASMUSSEN,  C.E.,  Builder 'of  the  Celebrated  Docks  at  Ham- 
burg: "Herr  Wurm,  member  of  parliament,  still  believes  in  the 
old  brewer  theory,  that  'good'  beer  will  banish  brandy  and  prevent 
ruin.  Another  Bavarian,  generally  regarded  the  most  eminent  author- 
ity in  the  department  of  hygiene,  Prof.  Max  von  Pettenkofer,  says 
the  contrary.  He  has  repeatedly  declared  that  the  above  opinion  does 
not  conform  to  fact ;  that  the  increased  use  of  beer,  not  only  fails  to 
diminish  the  use  of  brandy,  but  that  the  alcohol  swallowed  in  beer 
produces  the  same  drunkenness  and  a  variety  of  beer  diseases  into  the 
bargain." 

F.  VON  BIRCH-HIRSCHFELD,  M.D.,  Professor  of  Pathology  in  the 
University  at  Leipzig:  "Based  upon  my  experiences,  I  have  come  to 
the  conclusion  that  in  Leipsic,  as  in  other  large  cities,  a  very  great  pro- 
portion of  our  laboring  men,  perhaps  one-half  of  our  masculine  popula- 
tion twenty-five  years  old  and  upward,  manifest  more  or  less  organic 
injury  resulting  from  the  use  of  alcohol.  They  show,  withoiit  exception, 
a  decrease  in  the  number  of  tissue  cells  with  a  corresponding  loss  in 
power  and  endurance" 

GUSTAVE  VON  BUNGE,  M.D.,  Professor  of  Physiological  Chemistry, 
University  at  Basle:  "The  predisposing  cause  of  the  drink  habit  is 

1  There  are  no  italicized  statements  in  the  originals. 


THE  NERVOUS  SYSTEM  22 7 

not  wretchedness.  The  main  cause  is  the  imitative  passion  among  men. 
The  first  glass  of  beer  is  no  more  to  our  liking  than  our  first  cigar. 
Persons  drink  because  others  drink.  But,  after  the  habit  has  been 
formed,  there  is  never  any  lack  of  excuses  for  taking  a  drink.  People 
drink  when  they  meet ;  they  drink  when  they  part.  They  drink  when 
they  are  hungry  to  quiet  hunger;  they  drink  when  they  are  surfeited  to 
arouse  appetite.  They  drink  when  it  is  cold  for  warmth ;  they  drink 
when  it  is  hot  to  cool  off.  They  drink  because  they  are  sleepy  to  keep 
awake;  they  drink  when  they  cannot  sleep  to  induce  sleep.  They 
drink  because  they  are  sad;  they  drink  because  they  are  jolly.  They 
drink  because  there  is  a  baptism ;  they  drink  because  there  is  a  burial ; 
they  drink  and  they  drink.  Why  shouldn't  they  also  drink  to  forget 
care,  poverty,  and  wretchedness? 

"  But  among  all  excuses  to  drink,  the  latter  is  the  silliest.  A  man 
wants  to  do  away  with  an  effect,  and  increases  the  cause.  He  wants  to 
vanquish  poverty,  and  contracts  the  habit  of  spending  money  in  a  way 
that  interferes  with  his  capacity  for  work  and  for  making  money.  He 
wants  to  overcome  anxiety  and  care,  but  instead  of  going  to  some  true 
friend  who  can  lend  support  by  means  of  counsel  and  help,  he  resorts 
to  false  friends  at  the  saloon  who  say, « You  are  not  at  fault ;  it's  the 
condition  of  the  country/  and  who  kick  out  the  solace-seeker  as  soon 
as  he  is  no  longer  able  to  pay  his  bill  for  drink. 

"  Every  three  years  the  German  empire  expends  for  beer,  the  war 
indemnity  it  received  from  France,  five  billions  i  in  addition  to  that  it 
consumes  annually  even  more  distilled  liquors  per  capita  than  Russia, 
so  notorious  for  whiskey  drinking.  In  Germany  the  number  of  people 
who  are  annually  sent  to  hospitals  for  chronic  drunkenness  and  delirium 
tremens  is  increasing  at  a  frightful  rate,  attaining  for  the  last  year  for 
which  we  have  statistics,  11.974  (1885,  see  Baer).  And  now  bear  in 
mind  that  it  is  only  the  smallest  proportion  of  the  topers  who  consent 
to  enter  the  hospitals. 

"  Even  the  most  moderate  drinker  is  like  a  man  who  exclaims :  '  I  am 
never  dizzy,  it  is  fun  for  me  to  keep  my  balance  on  the  edge  of  a  preci- 
pice. I  oppose  having  any  railing  around.  Suppose  every  ninth  man 
does  fall  down  and  dash  out  his  brains  — what's  that  to  me?'  The  fall 
of  a  drunkard  is  often  much  more  shocking  and  horrible  than  that  from 
a  precipice,  because  the  drunkard  may  leave  a  degenerate  offspring  to 
be  slowly  tortured  to  death.  But,  finally,  what  is  the  use  of  moderate 
drinking,  of  keeping  one's  balance  on  the  edge  of  a  precipice  ?  That  the 
moderate  use  of  alcohol  is  destitute,  absolutely,  of  any  value,  is  apparent 
to  every  total  abstainer.  It  is  a  duty  to  build  around  a  precipice  a 
strong  railing.  That  railing  is  total  abstinence." 


228  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

ADOLF  FICK,  M.U.,  Professor  of  Physiology,  University  of  Wurz- 
burg,  Bavaria:  "We  often  hear  dissuasion  from  the  use  of  alcohol 
condemned  as  blameworthy.  They  say  wine  is  a  noble  gift  of  God, 
and  it  is  sinful  to  reject  instead  of  to  receive  it  with  gratitude.  It  is 
hard  to  believe  any  one  in  earnest  who  makes  this  statement.  We  may 
call  the  grapes  a  noble  gift  of  God;  wine  certainly  is  not,  for  we  never 
obtain  this  liquid  from  the  grape  except  by  artificial  means  specially 
designed,  by  means  of  a  process  much  resembling  rotting,  in  coopera- 
tion with  germs  that  have  been  added. 

"  About  two  years  ago  a  friend  of  mine  who  had  come  to  Wurzburg  on 
jury  duty  came  to  my  house  from  a  session  of  the  jury,  and  these  were 
his  first  words :  *  Remarkable,  in  every  crime  that  comes  up  before  us 
during  this  session,  alcohol  has  played  a  part ! ' " 

AUGUST  FOREL,  Professor  of  Mental  Diseases,  University  of 
Zurich,  Director  of  Insane  Asylum,  Burghozli,  near  Zurich :  "  Not  ab- 
stainers, but  the  advocates  of  the  possibility  of  universal  moderation 
are  the  visionary  people. 

"  Become  a  total  abstainer  from  alcohol ;  you  will  find  yourself  hap- 
pier, healthier,  and  stronger ;  you  will  be  rid  of  just  one  more  kind  of 
slavery ;  you  will  not  only  keep  your  high  spirits,  feel  jolly  and  sociable, 
but  these  qualities  will  improve  in  every  way.  You  will  become  suscep- 
tible to  the  higher  and  more  refined  enjoyments,  physical  as  well  as 
intellectual. 

"Where  is  the  boundary  between  the  drunkard  and  the  moderate 
drinker?  Nothing  appears  to  me  more  ludicrous  now  than  the  con- 
temptuous attitude,  the  moderate  drinker  assumes  toward  the  toper.  Do 
not  the  number  of  deaths  from  fatty  degeneration  of  the  heart,  diseases 
of  the  vessel  walls,  delirium  tremens,  the  hardening  of  the  liver,  preach 
loud  enough  that  our  drinking  customs  are  ruining  our  bodies  and  short- 
ening our  lives  ? 

"  The  role  alcohol  plays  in  student  life  is  one  of  the  darkest  chapters 
in  this  dark  history.  This  I  can  affirm,  that  in  Germany,  Switzerland, 
and  Austria,  yes,  and  in  France,  a  large  part  of  the  intellectual  power 
of  our  academic  youth  is  actually  drowned  in  beer  and  wine.  The  ridic- 
ulous drink  compulsion  and  idiotic  vainglory  at  the  drinking  festivals 
German  students  have  introduced  are  undoubtedly  the  most  hideous 
deformity  of  our  civilized  century.  At  the  same  time,  they  are  a 
revelation  of  the  mental  deficiency  among  our  university  students, 
the  intellectual  hope  of  our  nation.  Students  often  poke  fun  at  the 
Paris  fashions  of  the  woman  world',  —  I  am  also  heartily  opposed  to  their 
bad  taste  in  uniformly  aping  one  another,  according  to  the  change  of 
season,  which,  by  the  way,  has  this  in  common  with  the  drink  custom : 


THE  NERVOUS  SYSTEM  22Q 

it  puts  money  into  the  purses  of  a  few  schemers ;  —  but  how  much  more 
stupid,  and  in  how  much  poorer  taste,  are  the  students1  drinking  fash- 
ions!  People  call  it  jovial.  Yes,  a  pretty  joviality,  with  its  accom- 
paniment of  palsied  tongues,  staggering,  fighting,  vomiting,  in  which 
imbecility  is  applauded  and  beastliness  and  misdemeanors  are  excused 
nnd  glossed  over" 

FRIEDRICH  LUDWIG  JAHN,  Founder  of  the  German  Turn  Verein: 
"  We  must  again  train  our  young  men  to  remain  real  youth  that  will 
disdain  to  engage  in  even  allowable  pleasures  if  these  only  befit  the 
mature  years.  The  emotions  must  be  kindled  to  love  of  nature,  so  that 
they  will  experience  more  satisfaction  in  simplicity  than  in  the  drinking 
shops,  where  they  will  become  dull  and  nerveless.  In  Freiburg,  with 
its  more  than  1,000,000  grapevines,  I  still  manage  to  get  along  as  a 
water  drinker." 

K.  KROHNE,  D.C.L.,  Privy  Counselor,  Director  of  the  Prison  at 
Moabit  in  Berlin  :  "  Is  the  liberty  of  a  man  to  ruin  himself  and  family 
through  drink,  and  to  endanger  the  safety  of  society,  the  very  highest 
ideal  of  personal  freedom,  that  we  are  obliged  to  treat  it  as  something 
that  dare  not  be  disturbed  ?  Even  after  a  father  has  become  a  drunk- 
ard, allows  his  wife  and  children  to  go  hungry,  beats  them,  lets  his  chil- 
dren run  wild,  when  the  family  ruin  is  plainly  evident,  article  after 
article  of  furniture  being  pawned,  the  wretched  wife  sees  her  last  bed 
carried  away,  the  family  falls  upon  the  town,  the  father  becomes  a 
criminal,  and  brings  up  a  family  of  criminals,  —  even  then  we  are  not 
allowed  to  force  the  whiskey  bottle  from  his  hands." 

JUSTUS  VON  LEIBIG,  Chemist:  "It  is  now  possible  to  demonstrate 
with  mathematical  certainty  that,  so  far  as  enriching  the  blood  is  con- 
cerned, the  flour  that  will  lie  on  the  point  of  a  knife  affords  more 
nourishment  than  four  measures  of  the  best  Bavarian  beer ;  and  that 
anybody  who  drinks  a  measure  of  beer  daily  would  imbibe  in  one  year 
about  as  much  nourishment  as  is  contained  in  a  pound  of  bread." 

MARTIN  LUTHER  :  "  The  first  man  to  brew  beer  was  the  pest  of 
Germany  (tile  fuit  pestis  Germania}.  I  have  often  execrated  the 
one  who  first  brewed  beer.  Brewing  spoils  enough  barley  to  keep 
Germany." 

P.  J.  MOEBIUS,  M  D.,  Nerve  Specialist,  Leipzig:  "The  fact  is,  all 
this  talk  about  the  nutritive  value,  the  strengthening  and  curative  prop- 
erties of  alcohol,  is  nothing  but  a  cloak  the  drinker  employs  to  conctul 
his  appetite.  If  people  didn't  care  about  drinking,  nobody  would 
concern  himself  about  the  trifling  nutriment  claimed  for  alcohol. 


230  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

"  The  people  ought  to  be  enlightened  about  the  old  pretenses  that 
alcohol  nourishes,  warms,  strengthens,  aids  digestion,  cures ;  they  all 
amount  to  nothing.  Those  engaged  in  the  manufacture  and  sale  of 
liquor  are  a  great  power  —  wine  producers  and  sellers,  brewers,  dis- 
tillers, tavern-keepers,  and  all  their  hangers-on.  The  parents'  efforts 
ought  to  be  supported  by  the  teachers,  and  it  is  the  duty  of  the  clergy 
to  serve  the  cause,  not  only  by  precept,  but  also  by  force  of  example. 
It  is  of  greatest  importance  that  doctors  should  take  the  right  stand. 
Alas  !  until  the  present,  as  a  whole,  they  have  not  recognized  their 
duty  in  relation  to  drunkenness,  but  by  their  foolish  recommendations 
have  promoted  the  esteem  in  which  alcohol  has  been  'held.  To  be  sure, 
we  must  acknowledge  that  they  have  mostly  done  so  in  good  faith,  — 
correct  understanding  of  the  effects  of  alcohol  has  not  been  acquired 
until  recently,  and  it  has  not  yet  become  the  common  property  of  all 
physicians.  But,  at  this  day,  every  physician  ought  to  be  ashamed  to 
recommend  a  '  medicinal  -wine '  (there  is  no  such  thing  as  a  medicinal 
wine),  or,  what  is  more,  to  recommend  wine  as  a  tonic  for  children. 
Those  who  prescribe  a  special  brand  of  liquor  for  the  grippe  and  the 
like,  don't  know  what  they  are  about.  Every  physician  is  in  duty 
bound  to  be  strictly  temperate ;  if  he  were  a  total  abstainer,  his  example 
would  be  more  effective  than  that  of  others." 

L.  SONDEREGGER,  M.D. :  "  Thousands  boast  that  they  never  drink 
much,  especially  the  topers',  nobody  can  tell  them  the  truth  without 
suffering  for  it.  In  this,  also,  the  most  respectable  are  the  most  terrible 
sinners ;  never  quite  drunk,  but  daily  filled  with  drink,  they  are  like  a 
steam  boiler  heated  to  the  last  point  of  pressure,  trembling  under  the 
strain,  just  waiting  for  the  impulse  to  cause  an  explosion.  Look  at  this 
plump,  glowing,  red-cheeked  man ;  he  is  as  nervous  as  an  anemic  girl, 
sleepless,  out  of  humor,  bored  and  unhappy  under  brilliant  circum- 
stances; a  slight  illness  or  accident  would  take  him  to  his  grave. 

"  The  chief  opposition  towards  all  anti-alcohol  measures  proceeds  from 
people  concerned  in  the  business,  especially  from  the  manufacturer  of 
liquor,  to  whose  influence  it  can  be  ascribed  that  so  little  has  been 
accomplished." 


The  Body  has  a  Remarkable  Power  of  Adaptation. — 

Man  can  adapt  himself  to  more  climates  and  conditions 
than  any  other  animal,  the  dog  perhaps  ranking  next  in 
this  respect.  If  a  person  habitually  eats  too  much,  his 
stomach  becomes  enlarged  to  accommodate  the  foodo  If 


THE  NERVOUS  SYSTEM 

then  he  eats  a  smaller  but  sufficient  amount  of  food, 
he  still  has  a  craving  for  enough  to  fill  the  distended 
stomach.  In  a  few  days  the  stomach  shrinks  back  to  its 
normal  size,  and  the  appetite  also  becomes  normal.  The 
body  adapts  itself  to  unhealthy  conditions  too  readily  for 
its  own  welfare.  Confinement  and  idle  muscles  make  a 
man  restless  for  a  few  weeks,  but  if  he  represses  the  good 
instinct  he  soon  loses  all  desire  for  healthful  activity.  He 
even  gets  an  aversion  for  it,  although  it  may  be  just  what 
his  health  demands. 

Adaptation  to  Poisons.  —  Mithridates,  king  of  Pontus, 
suspected  his  enemies  of  intending  to  poison  him.  He 
therefore  took  poison  in  gradually  increasing  doses,  hoping 
his  body  would  become  so  used  to  poison  that  he  could  not 
be  poisoned.  Doubtless,  as  with  the  users  of  alcohol  and 
nicotin,  he  soon  had  a  craving  for  the  poisons,  however 
repulsive  they  may  have  been  at  first.  The  body  seems  to 
learn  to  defend  itself  against  poisons.  The  cells  burn  up 
the  poison  or  throw  it  off,  or  even  learn  to  tolerate  it,  yet 
their  vitality  is  doubtless  injured  by  the  task.  Some 
people  believe  that  this  adaptation  to  alcohol  and  tobacco 
means  that  they  are  harmless  or  even  beneficial ;  such 
people  generally  have  the  habit  of  using  them. 

People  with  Bad  Habits  who  live  to  Extreme  Age. — The 
power  of  the  body  to  defend  itself  against  stimulants  and 
narcotic  poisons  is  greater  if  the  person  using  them  leads 
an  outdoor  life.  The  oxygen  of  the  pure  air  helps  to 
burn  them  up,  the  muscular  exercise  of  an  outdoor  life 
keeps  the  skin  active  and  some  of  the  poison  is  excreted. 
We  sometimes  hear  of  people  who  live  for  a  century  in 
spite  of  using  tobacco.  Such  people  have  lived  out-of- 
doors  a  great  deal,  and  none  of  them  used  cigarettes  when 
children.  A  greater  number  of  temperate  than  intemper- 


232  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

ate  people  live  to  an  advanced  age.  Pure  air  and  an  active 
life  enable  the  body  to  free  itself  of  its  own  natural  waste 
material  and  of  narcotics  as  well.  Old  age  comes  on  from 
hardening  of  the  arterial  walls  by  the  deposit  of  mineral 
and  other  wastes.  A  man  is  said  to  be  "as  old  as  his 
arteries."  The  same  amount  of  tobacco  that  would  in  a 
few  years  ruin  the  health  of  a  man  working  in  an  office 
may  not  have  a  great  effect  upon  a  farmer. 

Presumption  and  Ignorance.  —  Many  people  think  they  are 
capable  of  tracing  the  effects  of  every  bad  habit  and  of  every 
drug,  and  of  measuring  exactly  what  the  effects  are.  Most 
people  who  use  alcoholic  drinks  and  tobacco  say  that  the 
habits  do  no  harm ;  a  few  even  say  that  such  things  benefit 
the  health.  Either  the  harm  done  in  their  cases  is  so  gradual 
that  it  is  not  noticed,  or  it  is  great  and  they  attribute  it  to 
something  else.  Rheumatism,  indigestion,  fatty  degeneration 
of  the  tissues,  kidney  troubles  are  among  the  more  marked 
but  often  unsuspected  effects  of  alcoholic  drinks.  Perhaps 
the  most  important  result  of  the  right  study  of  the  body  is 
the  realization  that  our  ignorance  of  the  body  is  many  times 
greater  than  our  knowledge  of  it.  People  who  have  only 
made  a  thoughtless  study  of  physiology  imagine  that  the 
body  is  a  very  simple  machine  and  if  it  goes  wrong  the 
disorder  can  be  remedied  in  a  twinkling.  If  one  has  a  bad 
cold  and  walks  down  the  street  almost  every  acquaintance  he 
meets  can  suggest  an  "  infallible  cure,"  simply  because  he 
took  it  once  when  his  cold  was  going  to  get  well  anyway, 
and  his  cold  ceased.  Because  a  man  was  sick  and  took  a  cer- 
tain drug  is  not  proof  that  it  cured  him  ;  its  narcotic  or 
stimulant  effect  may  have  delayed  the  cure.  Another  man 
may  fall  sick,  take  the  same  drug,  and  die ;  yet  this  is  not 
proof  that  the  drug  helped  to  kill  him  ;  we  do  not  know.  So 
many  people  would  not  be  foolish  enough  to  believe  patent 


THE  NERVOUS  SYSTEM  233 

l 

medicine  advertisements  if  they  did  not  think  they  were 
capable  of  prescribing  for  themselves.  They  take  drugs 
confidently  upon  the  advice  of  a  druggist,  while  a  physi- 
cian, who  has  devoted  years  to  the  study  of  drugs,  often 
prescribes  with  doubt  and  hesitation.  The  alcohol  or  opium 
in  the  patent  medicine  deadens  pain,  and  the  user  writes  a 
glowing  letter  in  its  praise.  When  he  becomes  worse  he 
will  never  attribute  the  effect  to  the  medicine. 

The  science  of  physiology  teaches  that  the  cells  have 
built  the  body  to  its  present  size,  that  they  sustain  it, 
that  they  repair  wounds  and  broken  bones,  and  only  they 
can  heal  the  body.  No  patent  medicine  vender  can  know 
what  is  being  done  by  these  wonderful  little  workers,  and 
he  manufactures  no  cure-all  that  can  surpass  them.  Fevers, 
inflammations,  and  other  diseases  are  attempts  of  the  cells 
to  burn  up  or  expel  poisons,  germs,  and  waste  material.  We 
can  aid  the  cells  best  by  pure  air,  simple  food,  cleanliness, 
rest,  and  healthful  activity.  To  stop  the  inflammation  or 
fever  before  it  has  done  its  work  is  to  thwart  the  efforts  of 
the  cells  and  perhaps  to  change  an  acute  disease  into  a 
chronic  one.  The  best  physicians  give  as  few  drugs  as 
possible,  especially  if  the  intelligent  cooperation  of  the 
family  enables  them  to  use  better  means.  It  seems  a 
wonderful  and  skillful  thing  when  a  person  is  racked  with 
pain  to  have  it  cease  after  a  physician  or  other  person  gives 
a  small  dose  of  opium  or  other  narcotic  drug,  but  any 
blunderer  can  do  it.  Narcotic  drugs  merely  paralyze  the 
healing  efforts  of  the  cells,  hide  the  disease,  and  leave  the 
physician  in  darkness  as  to  its  progress.  Skillful  physicians 
do  not  interfere  with  the  healing  efforts  of  the  body  itself 
but  cooperate  with  them.  Tens  of  thousands  of  morphine 
users  in  our  country  with  lives  hopelessly  wrecked  are  one 
of  the  results  of  prescribing  opium. 


234  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

Stimulating  the  Mucous  Membrane.  —  Calomel  stimulates 
the  epithelial  cells  lining  the  food  tube.  It  is  a  mineral 
poison  containing  mercury,  and  the  cells  pour  out  mucus 
profusely  to  wash  it  away  and  prevent  being  injured  (see 
the  dark  cells  in  Fig.  7).  When  the  body  is  being  re- 
lieved of  the  calomel  it  likewise  is  saved  from  absorbing 
undigested  food  which  has  fermented  in  the  intestine  and 
formed  poisons.  Thus  a  spell  of  sickness  may  be  post- 
poned ;  but  it  is  done  at  the  expense  of  exhausting  and 
injuring  the  intestinal  lining,  and  the  intestine  may  soon 
become  more  torpid  than  ever.  If,  in  spite  of  the  efforts 
of  the  cells,  calomel  is  absorbed  into  the  circulation,  it  may 
cause  a  loosening  of  the  teeth  and  salivation,  which  is  a  pro- 
fuse flow  of  saliva  to  aid  the  removal  of  the  poison.  Dys- 
pepsia and  thin  blood  often  result  from  taking  purgative 
medicine.  In  some  cases  the  cells  become  so  weakened  that 
they  will  not  secrete  at  all  unless  calomel  is  taken  regularly. 

Evils  of  Home  Dosing.  —  When  any  one  begins  to  feel 
bad  he  should  heed  the  warning  promptly  and  find  the 
fault  in  his  way  of  living  and  correct  it,  whether  it  be  in 
eating,  working,  or  otherwise.  In  some  families  ignorant 
of  hygiene  or  too  lacking  in  self-control  to  use  it,  parents 
are  ever  ready  for  home  doctoring  instead  of  teaching  the 
children  to  live  in  a  better  way.  A  drug,  such  as  calomel 
or  a  patent  medicine,  is  taken  whenever  any  one  feels  bad. 
As  a  result  of  the  periodic  dosing,  there  is  usually  not  a 
rosy-cheeked  child  in  the  family,  —  their  teeth  are  bad,  their 
blood  is  thin. 

Relation  of  Drugs  to  Hygiene.  —  When  a  person  has  the 
habit  of  working  little  and  eating  much,  the  food  tube 
becomes  overloaded,  the  food  changes  into  a  sour  or  fer- 
menting mass,  the  moldy  growth  soon  coats  the  tongue, 
the  appetite  is  gone,  and  the  person  is  almost  prostrated 


THE  NERVOUS  SYSTEM  235 

with  poisons  absorbed  from  the  food  tube  (a  condition 
usually  given  the  absurd  name  of  "  biliousness  ").  If  he 
takes  timely  warning,  drinks  plenty  of  water,  ceases  to  eat 
until  his  appetite  returns,  he  may  soon  be  well  again.  If 
he  goes  on  until  he  becomes  ill  in  bed,  his  chance  for  help- 
ing himself  is  lost;  a  physician  should  be  called  and  his 
directions  implicitly  obeyed.  A  person  who  has  not  wis- 
dom and  prudence  enough  to  use  pure  air  and  water, 
simple  food,  and  exercise  to  keep  himself  well  is  not  wise 
enough  to  use  drugs.  Drugs  usually  are  violent  poisons; 
a  physician  only  is  competent  to  give  them.  A  man  takes 
a  drug  which  relieves  the  food  tube ;  he  feels  better  for  the 
time ;  instead  of  being  ashamed  of  his  wrong  way  of  living 
he  is  very  much  elated  at  his  skill  and  feels  very  wise. 
He  is  encouraged  to  live  as  before  instead  of  resolving  to 
learn,  if  possible,  to  take  care  of  himself.  Until  the  laws 
of  hygiene  are  better  understood  and  more  fully  believed  in, 
drugs  will  have  a  useful  place. 

Sixty  years  ago  it  was  the  custom  to  bleed  patients  for 
nearly  every  ailment.  This  made  the  cells  hungry  and 
set  them  to  work,  and  enabled  a  careless  man  to  resume 
his  habit  of  eating  much  and  working  little.  So  violent  a 
remedy  often  repeated  weakened  the  cells.  Bleeding 
doubtless  saved  life,  yet  it,  together  with  the  large  doses 
of  strong  drugs  which  next  became  the  custom,  seems  to 
have  weakened  the  body  of  civilized  man  so  that  now 
bleeding  is  never,  and  large  doses  seldom,  resorted  to. 
Drugs  are  recognized  as  useless  in  consumption  and  a 
number  of  other  diseases.  Drugs  with  a  narcotic  or 
stimulant  effect  are  given  in  smaller  and  smaller  doses; 
alcohol  is  hardly  ever  given  by  physicians  of  the  pres- 
ent day.  At  this  rate,  in  fifty  years  a  physician  will 
as  rarely  think  of  using  a  poisonous  drug  for  medicine 


236  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

as  a  physician  now  thinks  of  drawing  blood  from  a 
patient  in  order  to  heal  him.  Already  baths  are  in 
general  use  for  reducing  fevers.  Dieting,  rest,  massage, 
and  other  hygienic  measures  are  more  and  more  relied  on 
by  physicians  as  the  intelligence  of  the  people  allows  it. 
'  There  are  fewer  patients  now  than  formerly  with  supersti- 
tious dread  of  fresh  air  and  cold  water  and  boundless 
faith  in  strychnin,  arsenic,  calomel,  alcohol,  and  other 
dangerous  drugs. 

Not  Certain  Stimulants  and  Narcotics  but  a  False  Belief 
must  be  Destroyed.  —  If  opium  were  destroyed,  cocaine 
might  be  used  in  its  place ;  if  tobacco  were  no  longer 
grown,  excessive  use  of  coffee  might  result.  Arsenic, 
strychnin,  quinine,  etc.,  are  each  used  as  stimulants  by 
some  people.  In  Brazil,  coffee  is  used  in  place  of  alco- 
hol. Twenty  and  thirty  cups  are  drunk  by  one  person 
in  a  day.  The  §razilians  say  that  coffee  to  be  good 
must  be  as  "black  as  night,  as  bitter  as  gall,  and 
as  hot  as  fire."  So  long  as  a  false -trust  in  stimulants 
and  narcotics  exists  it  would  be  an  endless  task  to  drive 
them  out  of  use  one  by  one  only  to  be  replaced  by  another. 
People  used  to  seek  the  "  philosopher's  stone,"  which  would 
turn  all  it  touched  into  gold ;  the  search  for  the  "  fountain 
of  youth  "  and  the  "  elixir,  or  water,  of  life  "  has  been  aban- 
doned. In  our  time  the  search  for  the  fountain  of  health 
in  stimulants,  narcotics,  and  tonics  is  as  common  and  as 
fruitless  as  the  foolish  quests  of  other  times.  Pure  food 
will  give  strength,  alcohol  will  not;  exercise  is  a  natural 
stimulant  to  the  circulation,  strychnin  is  not ;  fatigue  is  a 
good  narcotic  and  brings  healthy  sleep,  opium  will  not  ; 
right  thoughts  will  cure  nervousness,  tobacco  will  not,  but 
will  make  one  more  nervous  still. 

Natural  living  is  all   that  will  insure  health.     It  is  as 


THE  NERVOUS  SYSTEM  237 

necessary  for  a  wealthy  man  or  a  learned  man  to  use  his 
muscles  to  make  his  blood  flow  as  it  is  for  a  poor  man  or 
an  ignorant  one.  Worry  and  anxiety  will  break  down 
nerve  strength,  and  nothing  but  peace  of  mind,  pure  air, 
and  simple  food  will  build  it  up.  Most  people  are  wise 
enough  to  take  care  of  their  health  if  they  lead  simple 
natural  lives ;  no  one  is  wise  enough  to  take  care  of  his 
health  if  he  leads  an  artificial  life.  Deadening  narcotics 
and  stimulants  may  postpone  the  ruin,  but  it  will  be  all 
the  more  complete  and  hopeless  when  it  comes.  A  man 
who  cannot  take  care  of  an  ax,  and  allows  its  blade  to  rust 
and  its  handle  to  rot,  is  not  wise  enough  to  interfere  with 
nature  by  using  hot  seasoning  when  he  has  no  appetite, 
taking  a  stimulant  when  he  is  tired  and  a  narcotic  when 
he  is  restless  from  using  his  brain  too  much  and  his  mus- 
cles too  little. 

Doing  is  More  Difficult  than  Knowing.  —  The  clearest 
and  most  convincing  argument  against  the  use  of  alcohol, 
and  the  most  vivid  descriptions  of  its  ruinous  effects  con- 
tained in  any  text-book,  were  written  by  a  university  pro- 
fessor who  afterward  died  a  miserable  drunkard.  Every 
boy  who  studies  the  destructive  efforts  of  alcohol  as  out- 
lined in  this  book  will  doubtless  resolve  never  to  touch  it. 
He  should  make  the  resolution  with  a  determination  to 
keep  it,  in  spite  of  the  ridicule  of  ignorant  acquaintances 
or  the  example  and  persuasion  of  so-called  friends. 

EXERCISES  IN  WRITING.  —  Why  I  believe  in  studying  Physiology. 
A  Home  having  an  Intelligent  Housekeeper.  A  Home  having  an  Igno- 
rant or  Careless  Housekeeper.  A  Graceful  Form.  Why  Some  People 
are  Unhealthy.  Which  is  a  Surer  Sign  of  Lack  of  Wisdom  :  Poverty, 
the  Inability  to  make  Money,  or  111  Health,  the  Inability  to  take  Care 
of  the  Body  ?  Good  Habits.  Natural  Means  of  Cure  and  Drugs. 
The  Body  a  House.  The  Mind  and  Health.  Why  Illness  is  so  Com- 
mon ?  Several  Kinds  of  Health  Cranks.  Why  I  stopped  Smoking. 


CHAPTER   IX 

THE   SENSES 

Review  Questions  introducing  this  Chapter. — Where  in  the  skin 
do  the  nerves  end  ?  What  evidence  is  there  that  we  have  separate 
temperature  nerves  for  hot  and  for  cold  ?  How  can  the  temperature 
nerves  be  trained  ?  What  feeling  warns  us  to  take  exercise  ?  To 
cease?  Does  hunger  show  merely  a  condition  of  the  stomach  ?  Where 
are  papillae  found  in  the  skin  ?  What  do  they  contain  ? 

The  five  special  senses,  as  usually  named,  are  touch, 
taste,  smell,  sight,  and  hearing.  The  temperature  sense 
should  be  classed  as  a  sixth  special  sense.  All  other 
sensations  are  classed  as  general  sensations. 

Five  Differences  between  Special  and  General  Sensation. 
—  First,  the  nerves  of  special  sense  all  end  in  special 
organs  at  the  surface ;  for  instance,  the  touch  corpuscles 
are  for  touch,  the  eye  is  for  sight,  etc.  There  are  many 
nerves  in  the  body  that  do  not  end  in  special  organs  ;  these 
nerves  give  what  is  called  general  sensation.  A  second 
difference  is  that  general  sensation  tells  of  the  condition  of 
the  interior  of  the  body,  while  special  sensations  tell  us  of 
the  condition  of  the  surface  of  the  body  and  of  the  out- 
door world.  Third,  general  sensations  are  not  so  exact 
as  the  reports  of  the  special  senses.  One  can  locate 
a  point  on  the  skin  that  has  been  touched  much  more 
accurately  than  he  can  locate  an  internal  pain.  A  fourth 
difference  is  that  the  meaning  of  each  special  sensation 
must  be  learned  (usually  in  infancy) ;  but  the  meaning  of 
general  sensations  is  inherited.  This  inherited  knowledge 
of  what  general  sensations  mean  is  also  called  instinct. 

»  238 


THE  SENSES 


239 


Fifth,  the  sympathetic  nerves  usually  bring  general  sensa- 
tions;  the  spinal  and  cranial  nerves  usually  bring  special 
sensations. 

Examples  of  general  sensations  are  hunger,  thirst,  satiety, 
nausea,  faintness,  giddiness,  fatigue,  weight,  aching,  shud- 
dering, creepy  feeling,  tingling,  sleepiness,  pain,  illness. 
Any  nerve  can  convey  the  general  sensation  of  pain,  if 
injured  along  its  course.  If  a  nerve  of  touch  is  cut,  there 
is  no  sensation  of  touch,  but  of  pain.  Touch  sensations 
come  only  from  the  ends  of  the  nerves.  General  sensa- 
tions are  of  many  kinds. 
We  are  only  half  con- 
scious of  some  of  them; 
many  of  them  are  hard 
even  to  describe. 

Hygiene  of  the  Gen- 
eral Sensations.  —  Gen- 
eral sensation  is  an 
invaluable  aid  to  the 
health.  Without  it  as 
a  guide,  the  body  could 
not  remain  alive  a  single 
day.  Pain  should  be 
heeded  as  our  best 
friend,  and  not  killed 
with  poisonous  drugs  as  if  it  were  our  worst  enemy.  We 
should  not  deaden  the  stomach  ache  with  an  after-dinner 
cigar.  If  we  do  not  go  to  bed'when  sleepy,  the  desire  for 
sleep  may  leave  us,  and  we  will  undergo  untold  suffering 
from  sleeplessness.  Thirst  should  be  satisfied  with  cool 
water,  which  quenches  it  the  best :  he  who  makes  his  teeth 
ache  with  ice  water  will  inflame  his  stomach  and  be  con- 
tinually thirsty.  He  who  does  not  stop  eating  when  his 


FIG.  161.  — DIFFERENT  KINDS  OF  TOUCH 
BODIES  AT  ENDS  OF  NERVES. 

A,  from  cornea  of  the  eye;  B,  from  the  tongue  of  a 
duck;  C,  D,  E,  from  the  skin  of  the  fingers.    (Jegi.) 


240  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

hunger  is  satisfied  will  distend  his  stomach  with  food,  and 
the  stretched  organ  will  be  harder  to  satisfy  thereafter ;  in 
fact,  eating  after  a  feeling  of  satiety  may  cause  indigestion 
so  that  the  cells  will  not  get  the  food.  A  dyspeptic  is 
always  hungry,  for  the  cells  are  starving.  Fatigue  of 
body  or  mind  gives  us  wise  counsel ;  but  this  feeling  may 
be  deadened  by  alcohol  or  tobacco,  and  work  continued 
until  the  body  is  injured.  We  should  heed  the  warning  of 
pain  or  fatigue  as  promptly  as  an  engineer  heeds  a  red 
flag  on  the  railway  track.  One  who  uses  narcotics  acts 
like  a  reckless  engineer  who  removes  the  danger  signal 
and  goes  ahead,  hoping  by  good  luck  to  escape  an  accident. 
Most  of  the  nerves  of  touch  end  in  papillae  of  the  der- 
mis  as  microscopic,  egg-shaped  bodies  (Fig.  186).  There 
are  also  many  in  the  interior  of  the  mouth,  especially  on 
the  tongue.  On  the  palms  they  are  arranged  in  curved 
lines,  and  on  the  tips  of  the  fingers  they  are  in  circular 
lines,  with  one  papilla  in  the  center.  The  delicacy  of  the 
sense  of  touch  varies  very  much  in  different  parts  of  the 
skin.  This  delicacy  refers  to  two  things:  the  ability  to 
feel  the  slightest  pressure  and  the  ability  to  tell  the  exact 
point  of  the  skin  that  is  touched.  A  lighter  pressure  can 
be  felt  on  the  forehead  and  temples  than  with  any  part  of 
the  body.  (Why  is  it  best  for  this  to  be  the  case  ?)  The 
greatest  ability  in  locating  the  point  of  the  skin  touched 
is  possessed  by  the  tip  of  the  tongue,  the  lips,  and  the 
ends  of  the  fingers.  (Why  is  it  best  that  this  is  so?) 
This  is  dullest  in  the  middle  of  the  back.  Its  delicacy 
varies  with  the  number  of  touch  corpuscles  in  different 
parts  of  the  skin.  This  sense  is  capable  of  great  cultiva- 
tion. Blind  people  read  by  pressing  their  fingers  over 
raised  letters,  yet  if  you  tried,  you  could  not  feel  the 
difference  between  the  letters. 


THE  SENSES  241 

Experiment  35.  Open  a  pair  of  scissors  so  that  the  points 
are  one  eighth  of  an  inch  apart,  and  touch  both  points 
to  the  tip  of  the  finger.  Are  they  felt  as  one  or  as  two 
points  ?  Find  how  far  they  must  be  separated  to  be  felt 
as  two  points  when  applied  to  the  back  of  the  neck. 
Caution  :  The  person  should  be  blindfolded,  or  should  look 
away  while  the  tests  are  being  made.  Two  pins  stuck 
in  a  cork  will  be  more  convenient  to  use  than  scissors. 

The  temperature  sense  has  been  discussed  in  the  chap- 
ter on  the  skin.  Review  the  topic  on  the  thermic  nerves. 
That  the  thermic  nerves  are  easily  fatigued  is  noticed  soon 
after  entering  a  bath  of  hot  water ;  it  is  also  shown  by  the 
fact  that  in  cold  countries  the  nose  or  ears  of  a  person  may 
freeze  without  his  feeling  it. 

Warm  objects  give  heat  to  the  skin,  hence  they  feel 
warm.  Cold  objects  take  away  heat  from  the  skin,  and  feel 
cold.  The  temperature  nerves  end  throughout  the  skin 
(Fig.  162)  and  in  the  mucous 
membrane  of  the  mouth,  phar- 
ynx, gullet,  and  nostrils.  Why 
are  they  needed  in  those  places? 
The  skin,  cheeks,  -eyelids,  and 
elbows  are  especially  sensitive  to 
heat  and  cold.  The  laundry 


FIG.  162.  —  "Cold"  spots  (light shad- 
WOm  an  tests  a  hot  iron  by  hold-          ing).     "  Hot"  spots  (dark),  skin 

ing  it  near  her  cheek.    A  nurse 

tests  the  water  of  a  child's  bath  with  her  elbow.  In  wash- 
ing the  face  with  water  that  is  too  hot  the  eyelids  suffer 
most.  The  eyes  are  easily  injured  by  heat;  hence  this 
provision  for  their  protection.  Glass  blowers  disregard 
this  feeling,  and  many  of  them  go  blind  by  the  time  they 
are  forty  years  old.  Students  find  that  hot,  dry,  stove- 
heated  rooms  or  hot  lamps  cause  trouble  with  the  eyes. 
R 


242  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

The  Muscular  Sense.  —  There  has  been  much  discussion 
as  to  whether  this  is  a  special  sense.  No  special  end  organs 
have  been  discovered,  and  it  partakes  of  the  nature  of  gen- 
eral sensation.  The  special  sense  of  touch  gives  some  sense 
of  weight.  A  weight  upon  the  skin  must  be  increased  by 
one  third  before  it  feels  heavier,  but  by  lifting  an  object  so 
as  to  bring  into  action  the  muscular  sense  residing  in  nerves 
ending  in  the  muscles  an  increase  of  only  one  seventeenth 
of  the  original  weight  will  be  noticed.  This  sense  gives 
us  a  continual  account  of  the  position  of  the  limbs. 

Experiments. — 36.  Make  tests  of  the  ability  to  distin- 
guish the  weights  of  objects  weighing  nearly  the  same. 
37.  Close  the  eyes  and  let  a  friend  move  your  arm  a  few 
inches;  then  see  if  you  can,  with  the  other  hand  touch 
the  hand  in  its  new  position  at  the  first  attempt.  ^ 

REVIEW  BASED  ON  FIGURES.  —  A  number  of  pupils  may  draw  upon 
the  blackboard  and  explain  the  following  figures :  2,  7,  10,  20,  32,  43, 
44,  48,  49,  52,  55,  85,  90,  93,  99,  100,  101,  102,  104,  105,  107,  108,  109; 
112,  116,  117,  118,  120,  121,  123,  124,  125;  131,  133,  135,  136,  137,  part 
of  138,  141,  142,4,  144,  145,  146,  150,  151,  152,  154,  157,  159,  1 60,  162. 

THE  SENSE  OF  TASTE 

The  end  organs  of  taste  are  located  in  the  papillae  of 
the  tongue.  The  tongue  has  a  fuzzy  look  because  of  the 
numerous  papillae.  The  papillae  on  the  tongue  are  of 
three  kinds  (see  Fig.  163,  also  use  a  mirror),  i.  The 
threadlike  papillce  are  numerous  on  the  sides  and  tip 
of  the  tongue,  and  are  believed  to  be  of  use  chiefly  in 
touch.  2.  The  mushroom  papillce  are  larger  but  less 
numerous  than  the  threadlike  papillae,  and  are  scattered 
among  the  latter  on  the  sides  and  tip  of  the  tongue. 
3.  The  large  walled  papillce  number  only  eight  or  ten,  and 
are  situated  in  a  V-shaped  line  far  back  on  the  tongue,  with 


THE  SENSES 


243 


FIG.  163.— THE  TONGUE  AND  LOWER  TEETH. 

i,  thread-like  papillae:  a,  2,  mushroom  papillae;    4,  walled 
papillae;  5,  tonsil. 


the  point  of  the 

V    toward     the 

throat.  Each  one 

is  surrounded  by 

a     ditch,    and 

beyond    this,    a 

wall  of  mucous 

membrane.  The 

nerves   of   taste 

end  in  the  last 

two    classes    of 

papillae. 

The  principal 

tastes  are  only 

four;    namely, 

sour   and  sweet 

(tasted  chiefly 

by  edges  of  tongue),  saline  and  bitter  (tasted  on  the  back 

of  tongue). 

Experiments.— 38.  Put 
a  little  vinegar  on  the 
back,  tip,  and  edges  of 
the  tongue.  Where  is  the 
taste  strongest  ?  39.  Try 
sugar,  salt,  and  quinine  in 
the  same  way. 

The  nerves  of  smell  end 
in  the  mucous  membrane 
of  the  upper  half  of  the 
two  nasal  chambers  (Fig. 
1 64) ;  the  fibers  are  spread 
over  the  upper  proportion 
of  the  walls.  The  direct 


FIG.  164.  — OUTER  WALL  OF  LEFT  NASAL 
CAVITY. 

Olfactory  nerve  forms  a  bulb.  /.  on  the  floor  of  the 
skull.  The  fibers  branch  from  this  bulb  like 
the  roots  of  an  onion  and  spread  out  on  the 
walls  of  the  nasal  chamber.  St,  Mt,  ht  turbi- 
oate  bones.  /*<*,  hard  palate. 


244  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

current  of  air  does  not  pass  as  high  as  these  nerve  end- 
ings; hence  sniffing  aids  the  perception  of  odors.  This 
sense  is  able  to  bring  up  the  associations  of  early  life 
more  powerfully  than  any  of  the  senses.  The  odor  of 
a  flower  like  one  that  grew  in  an  old  garden  can  almost 
restore  the  consciousness  of  the  past.  We  smell  gases 
only;  solids  and  liquids  cannot  affect  the  nerve. 

Flavors. — The  tastes  that  we  call  flavors  are  really 
smells.  We  confuse  them  with  taste,  because  they  accom- 
pany food  that  is  in  the  mouth.  Name  some  foods  that 
seem  "tasteless"  when  one  has  a  severe  cold  in  the  head. 
Why  is  this  ?  Some  of  the  most  repulsive  drugs  can  be 
easily  swallowed  if  the  nose  is  held. 

Experiment  40.     Mark  F,  T,  or  FT  after  the  following 
foods,   according    as    they    have   flavor,   taste,   or   both : 
vanilla,          apple,          lemon,          beef,          peaches, 
grapes,  coffee,  onion,  potato,  cinna- 

mon. A   good   test  for   the    presence    of   flavors   is 

whether  they  can  be  smelled  without  being  chewed. 

Experiment  41.  Blindfold  a  member  of  the  class,  and 
while  he  holds  his  nostrils  firmly  closed  have  him  place 
successively  upon  his  tongue  a  bit  of  apple,  potato,  and 
onion.  Can  he  distinguish  them? 

HYGIENE  OF  THE  SENSES   OF  TASTE  AND  SMELL 

Their  Value  as  Guides.  —  A  savage  or  a  beast  uses  the 
senses  of  taste  and  smell  to  find  out  whether  things  are 
good  to  eat  or  not.  If  a  civilized  man's  senses  are  not 
perverted,  and  he  eats  only  simple  foods  that  have  a 
pleasant  taste,  they  will  not  injure  him  or  cause  him  sick- 
ness. Things  that  are  poison  usually  have  an  unpleasant 
taste  and  often  have  an  unpleasant  odor.  These  senses 


THE  SENSES 


245 


are  naturally  of  wonderful  delicacy.  They  can  be  culti- 
vated to  a  still  more  remarkable  degree,  or  they  can  be 
blunted  and  almost  destroyed. 

Experiment  42.  Blindfold  pupils  and  test  the  sense  of 
smell  with  perfumes,  fruits,  extracts,  flavors,  drugs,  etc. 

How  the  Sense  of  Smell  is  Injured.  —  Some  persons  live 
so  carelessly  as  to  bring  on  a 
constant  succession  of  colds. 
By  continuing  in  faulty  ways 
of  living,  the  colds  change  into 
a  chronic  catarrh  which  so  af- 
fects the  mucous  membrane  in 
the  upper  part  of  the  nose  as  _r.:z?-( 
to  dull  or  destroy  the  sense  of 
smell  (see  Fig.  164,  also  Fig. 
165).  Then  the  enjoyment  of 
delightful  odors  and  agreeable 
flavors  is  impossible,  and  the 
body  loses  an  ever  vigilant  pro- 
tector placed  as  a  sentry  to  warn  against  the  admission 
of  poisonous  food  and  gases. 

Effect  of  this  Injury  upon  Habits  of  Eating.  —  The  loss 
or  even  the  weakening  of  the  perception  of  flavors  is  an 
injury  to  the  working  of  the  closely  related  sense  of  taste. 
When  a  person  loses  the  enjoyment  of  delicate  flavors,  he 
wants  food  to  have  strong  seasoning  and  more  decided  taste 
to  prevent  it  from  being  insipid.  Everything  must  be 
either  very  greasy  or  very  sweet  or  very  salty  or  very 
sour,  to  please  his  degenerate  senses.  Wheat,  corn,  and 
other  grains  have  each  its  own  pleasant  taste,  yet  such  per- 
sons must  have  lard  in  their  bread  because  they  are  not 
capable  of  appreciating  anything  with  a  delicate  taste.  In 
England,butter  is  not  salted  and  its  delicate  taste  is  enjoyed ; 


FIG.  165.  — CROSS  SECTION  OF 
NASAL  CHAMBERS. 


246  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

in  America,  salt  is  added  to  preserve  it,  and  most  people 
have  come  to  prefer  the  strong  taste  of  salty  butter  to  the 
delicate  taste  of  pure  butter,  and  do  not  like  it  unless  its 
true  taste  is  partly  hidden  by  the  taste  of  salt. 

Bad  cooks  have  injured  our  perception  of  tastes  and  of 
flavors  by  making  mixtures  that  confuse  the  senses. 
After  they  drive  off  the  flavors  by  overheating,  they 
have  to  add  vinegar,  grease,  etc.,  to  prevent  the  food 
from  being  entirely  without  taste  or  flavor.  In  Spain,  the 
cooks  mix  foods  together  more  than  in  many  countries,  and 
give  most  dishes  a  strong  odor  of  garlic  in  an  attempt  to 
undo  the  evil.  In  Mexico,  enormous  quantities  of  hot 
pepper  are  used.  Many  persons  have  catarrh  of  the 
stomach  in  consequence.  Would  you  say  that  a  kitchen 
from  which  savory  odors  of  the  food  permeate  the  neigh- 
borhood during  the  time  of  cooking,  contained  a  good  cook 
or  a  poor  one  ?  Should  flavors  be  driven  off  or  retained 
in  the  food  ?  Often,  because  of  strong  seasoning,  people 
eat  more  than  the  body  demands.  Tender  lettuce,  water 
cress,  etc.,  are  palatable  without  seasoning,  and  too  much 
will  not  be  eaten,  but  the  stomach  is  sometimes  overloaded 
with  tough  weedy  vegetables  like  turnip  tops,  cabbage,  etc., 
because  of  the  high  seasoning.  For  one  to  know  how 
much  of  such  foods  he  really  likes,  he  should  try  to  eat 
them  without  mixing  condiments  with  them. 

Deceiving  the  Sense  of  Taste.  —  The  habit  of  using  nar- 
cotics like  tea  and  coffee  is  usually  begun  by  concealing  the 
repulsive  bitter  taste  of  the  substance  by  mixing  sugar, 
cream,  and  other  agreeable  things  with  it.  Licorice  is 
sometimes  mixed  with  tobacco  to  weaken  its  biting  taste. 
Pure  alcohol  would  never  be  drunk  by  any  one  who  had  the 
least  respect  for  the  sense  of  taste,  but  the  agreeable  flavor 
of  grapes,  apples,  and  other  fruit  which  still  remains  in 


THE  SENSES  247 

wine,  cider,  and  brandy,  conceal  the  repulsive  taste  of  the 
alcohol.  Beer  has  the  insipid  taste  of  grain  which  has 
undergone  decomposition  or  partial  rotting,  and  hops  are 
added  because  the  strong  taste  of  hops  obscures  the  stale, 
insipid  taste  of  the  rotted  grain.  Eggnog  is  made  of  eggs, 
a  nourishing  food;  sugar,  which  has  an  agreeable  taste; 
water,  a  refreshing  drink ;  and  alcohol,  a  fiery  poison. 
A  very  good  eggnog  is  often  made  without  alcohol,  but 
a  good  one  could  hardly  be  made  with  any  of  the  pleasant 
ingredients  left  out.  The  best  eggnog  is  made  by  using 
the  fresh  juice  of  lemon,  orange,  or  grape,  instead  of 
alcohol. 

Effect  of  Narcotics.  —  Tobacco,  alcohol,  opium,  and  other 
narcotics  dull  the  senses  of  taste  and  smell  and  prevent  the 
enjoyment  of  delicate  flavors.  They  accomplish  this  as 
much  by  their  effect  upon  the  brain  as  upon  the  nerves 
themselves. 

It  is  Wrong  to  eat  Food  that  is  not  Relished.  —  Unpala- 
table food  is  not  likely  to  be  well  digested.  It  is  a  law  of 
the  body  that  the  food  which  is  enjoyed  the  most  is  digested 
the  best.  This  applies  to  food  with  its  own  honest  taste, 
not  to  food  disguised  by  the  taste  of  something  else. 
The  rule  does  not  apply  to  a  taste  perverted  by  having 
been  forced  to  become  accustomed  to  poisonous  things. 
People  who  munch  their  food  slowly  enjoy  the  pleasures 
of  taste  the  most,  and  digest  their  food  the  best.  The 
nerves  of  taste  and  smell  easily  become  fatigued.  The 
first  whiff  from  a  cologne  bottle  is  the  strongest.  Highly 
flavored  foods  should  be  eaten  moderately,  if  we  would 
obtain  the  greatest  enjoyment  from  them. 

THOUGHT  QUESTIONS. —  1.  Interfering  with  the  Body.  What  is 
the  natural  direction  of  growth  of  the  big  toe  ?  2.  Think  of  six  evil 
results,  direct  or  indirect,  which  will  follow  from  displacing  it  by  tight 


248  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

shoes,  (p.  67.)  3.  Which  part  of  the  spinal  column,  designed  in 
infinite  wisdom  to  be  most  flexible,  do  some  people  try  to  make  the 
most  inflexible  ?  4.  The  mobility  of  the  false  and  floating  ribs  was 
intended  as  a  blessing.  Some  people  interpret  the  blessing  as  an 
opportunity  to  do  what  ?  5.  Name  six  articles  which  warn  us  to  avoid 
them  by  their  bitter,  burning,  or  nauseating  tastes,  yet  which  are  used 
by  man.  6.  Name  six  feelings  which  are  intended  as  warnings  for  our 
guidance,  but  which  are  commonly  disregarded. 


THE   EYE   AND   SIGHT 

Sound  reaches  the  ear  by  means  of  a  trembling,  or  shak- 
ing, in  the  air  called  sound  waves.  Light  reaches  the  eye 
by  means  of  tremblings,  or  waves,  in  a  fluid  much  thinner 
than  the  air,  called  the  ether.  Ether  fills  the  space  be- 
tween the  particles  of  air.  High  up  above  the  earth, 
where  air  no  longer  exists,  the  ether  alone  is  found  ;  it 
extends  to  the  sun,  moon,  and  stars,  and  brings  energy 
from  them  to  us  in  the  form  of  light.  The  waves  of 
light  make  no  impression  upon  any  nerve  except  the 
nerve  of  the  eye,  called  the  optic  nerve. 

The  sense  of  sight  enables  us  to  avoid  dangers  when 
we  move  about,  to  judge  of  the  distances  of  objects,  to 
observe  the  various  forms  of  material  things,  and  to  enjoy 
the  varying  lights  and  shadows,  colors  and  tints. 

The  eyeballs  are  globes  about  an  inch  in  diameter. 
They  are  placed  in  deep,  bony  sockets,  called  orbits,  in 
the  front  part  of  the  skull  (Fig.  43).  The  optic  nerve, 
other  nerves,  and  several  large  blood  vessels  pass  to 
the  eye  through  a  hole  in  the  back  of  the  orbit.  A 
soft  cushion  of  fat  is  in  the  orbit  behind  the  eye- 
ball. A  pressure  upon  the  eyeball  causes  the  eye  to 
sink  into  the  socket,  for  the  fat  yields  to  the  pressure. 
This  is  a  protection  to  the  eye.  In  heads  of  the  same  size, 
there  is  very  little  difference  in  the  size  of  the  eyeballs. 


THE  SENSES  249 

The  reason  that  some  persons  appear  to  have  much  larger 
eyes  than  others  is  because  some  eyes  are  not  set  so  deep 
in  the  sockets,  or  because  some  persons  keep  the  eyes 
wide  open,  while  others  keep  the  lids  partly  closed  over 
the  ball.  The  eyeball  itself  has  hardly  any  power  of 
changing  its  expression.  The  expression  of  the  eye 
comes  from  the  movements  of  the  ball  and  lids. 

The  eyelids  protect   the  eyes  from  dust,  and  at  times 
from  the  light.     They  are  aided  in  this  by  the  eyelashes. 

The  tears  are  formed  by  tear  glands  situated  above  the 
eyeball  in  the  portion  of  the  orbit  farthest  from  the  nose, 
just  beneath  the  bony  brow 
where  it  feels  the  sharpest 
(Fig.  1 66).  They  are  about 

the  size  of  almonds.  A  salt-  vS?i^^S«HBfc^il^  .Uucto 
ish  liquid  is  continually  ooz- 
ing from  the  tear  glands  and 
passing  over  the  eyeball; 
it  is  carried  into  the  nose 
through  the  nasal  duct  (Fig. 
1 66).  The  tears  reach  this 

duct  through  two  small  canals,  which  open  into  the  eye 
in  the  little  fleshy  elevation  at  the  inner  corners  of  the 
eye  (Fig.  166).  The  opening  of  one  of  the  canals  may 
be  seen  by  looking  into  a  mirror.  Sometimes  these  canals 
are  stopped  up,  and  what  is  called  a  "  weeping  eye " 
results.  A  temporary  stoppage  may  occur  during  a  cold 
in  the  head.  Sometimes,  under  the  influence  of  anger 
or  other  strong  emotion,  the  tears  may  be  formed  so  fast 
that  they  cannot  be  carried  to  the  nose  and  they  flow 
down  the  cheek.  Usually  the  tears  are  evaporated  on 
the  warm  mucous  lining  of  the  nasal  cavities.  A  crying 
child  makes  frequent  swallowing  movements  (spoken  of 


250 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


as  "  gulping  down  his  anger ") ;  these  movements  are 
caused  by  the  need  of  swallowing  the  extra  tears  that 
reach  the  throat.  The  front  of  the  eye  is  as  transparent 
as  clear  glass;  the  lids  and  the  tears  help  to  keep  it 
clear  by  performing  a  service  for  it  like  that  which  a 
servant  performs  who,  with  cloth  and  water,  frequently 
polishes  a  plate  glass  window.  Tears  prevent  friction 
between  eye  and  lid.  Winking  applies  the  tears  to  the 
ball.  Small  glands  along  the  edges  of  the  lids  form  a 
kind  of  oil  which  usually  prevents  the  tears  from  flow- 
ing over  the  lids.  Sometimes  this  oily  secretion  is  so 
abundant,  especially  during  sleep,  as  to  cause  the  lids 
to  stick  together. 

The  globe  of  the  eye  consists  of  its  outer  wall  and  the  soft 
contents  within  the  wall  (Fig.  167).     The  wall  has  three 

layers  or  coats, 
and  the  contents 
are  in  three  divi- 
sions. 

The  outer  coat 
is  the  tough  scle- 
rotic (Greek,  skle- 
ros,  hard),  com- 
posed of  dense 
connective  tissue. 
It  gives  strength 
and  firmness  to 
the  eyeball.  It 
shows  between  the  lids  as  the  "white  of  the  eye."  It  is 
white  and  opaque  except  in  front ;  there  it  bulges  out  to 
form  the  transparent  cornea.  This  clear  portion  of  the 
wall  may  be  seen  by  looking  at  the  eye  of  another  from 
the  side. 


FIG.  167.  — THE  ANATOMY  OF  THE  EYE. 


THE  SENSES 


251 


The  second  coat,  called  the  choroid  (Fig.  168),  consists 
of  blood  vessels  and  a  loose  connective  tissue  containing 
many  dark  brown  or  black  pigment  granules.  The  choroid 
absorbs  light.  Cats'  eyes  shine  at  night  because  this  coat 
in  their  eyes  reflects  some  light.  The  choroid  separates 
from  the  sclerotic  toward  the  front  of  the  eye  and  forms 
the  colored  iris.  The  iris  makes  the  eyes  beautiful,  and  it 
also  serves  the 
useful  purpose  of 
regulating  the 
amount  of  light. 
The  hole  in  the 
iris  is  called  the 
pupil. 

The  third  and 
innermost  coat, 
called  the  ret'i-na, 
is  the  most  impor- 
tant and  charac- 
teristic tissue  in 
the  eye.  It  is 
made  by  the  fibers 
of  the  large  optic 
nerve.  This  nerve  contains  about  five  hundred  thousand 
fibers,  and  enters  at  the  back  of  the  ball.  The  spot  where 
it  enters  contains  no  nerve  endings  and  is  not  sensitive  to 
light.  It  is  called  the  blind  spot. 

Experiment  43.     In  this  experiment  shut  the  right  eye 
and  be  careful  not  to  let  the  left  eye  waver. 

*  Read  this  line  slowly.     Can  you  see  the  star  all  the 
time  ? 

Within  the  coats  of  the  ball,  like  the  pulp  within  the  rind 
of  an  orange,  are  the   soft  contents,  divided  into  three 


FIG.  168.  — THE  CHOROID  COAT,  b,  AND  IRIS,  c,  ex- 
posed by  cutting  and  turning  back  of  sclerotic  and 
cornea;  et  one  of  the  nerves  of  iris ;  /  blood  vessel. 


252 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


parts.  The  first  is  a  watery  liquid  in  front,  which  serves 
to  keep  the  cornea  bulged  out  (Fig.  167).  It  is  called  the 
a* que-ous  hu1  mor.  The  main  cavity  of  the  ball  is  occupied 
by  a  clear  jelly  like  substance  called  the  vit' re-ous  humor, 
which  serves  to  keep  the  ball  distended.  Back  of  the  iris, 
and  separating  the  two  humors  just  named,  is  the  crystal- 
line lens,  a  beautiful  clear  lens,  rounded  out  on  both  sides 
(convex).  It  serves  to  bring  the  light  to  a  focus  on  the 
retina,  thereby  forming  images  of  outside  objects. 

Muscles  of  the  Eye.  —  It  would  be  a  great  task  to  turn 
the  head  every  time  one  desired  to  look  at  an  object  in 
another  direction.  There  are  six  pairs  of  muscles  that  roll 
the  eye  around  in  its  bed  of  fat  to  any  desired  direction 

(see  Fig.  169). 
They  cause  both 
eyes  always  to 
move  together. 
The  eye  niuscles 
are  so  important 
that  three  of  the 
twelve  pairs  of 
cranial  nerves 
send  fibers  to  these 
muscles.  These 
nerves  and  mus- 
cles play  an  im- 
portant part  in  thinking.  It  is  found,  for  instance,  that  we 
cannot  distinctly  imagine  a  herd  of  sheep  jumping  over  a 
fence  one  after  another,  without  slightly  moving  the  eye- 
balls. Aided  by  these  muscles,  some  pupils  remember  on 
which  part  of  the  page  each  topic  in  the  lesson  happens  to 
be  printed.  This  learning  of  accidental  relations,  instead 
of  logical  relations,  prevents  the  mastery  of  a  subject. 


C.A. 


FIG.  169.  —  MUSCLES  OF  RIGHT  EYEBALL  (seen  from 
above) ;  MUSCLES  OF  LEFT  EYEBALL  (seen  from 
the  side). 

C.h,t  junction  and  crossing  of  optic   nerves;  S.Ob.,  muscle 
that  passes  through  a  pulley. 


THE  SENSES 


253 


The  eye,  like  a  camera,  has  a  dark  lining  (the  choroid) ; 
the  retina  corresponds  to  the  sensitive  plate,  and  the  lens 
brings  the  rays  to  a  focus  on  it  and  forms  the  image. 

The  Path  of  Light  in  the  Eye.— The  light  enters  through 
the  transparent  cornea  and  passes  through  the  aqueous 

A 


FlG.  170.  —  Image  of  object  in  eye  is  small  and  inverted. 

humor.     As  it  goes  through  the  pupil,  the  iris  shuts  off 

all  the  light  that  is   not   needed.      The   crystalline   lens 

receives  the  light  that  has  been  allowed  to  pass,  and  so 

bends  the  rays  (Fig.   170)  that  by  the  time   they   have 

passed  through  the  vitreous  humor  they 

fall  upon  the  retina  in  just  the  right  way 

to  form  a  tiny  image  of  anything  outside. 

The  choroid  absorbs  any  light  that  passes  FIG.  171.—  A  coin 

the  retina.     The  iris  and  choroid  of  albi- 

nos  have  no  pigment;   hence  they  squint 

their  eyes. 

Experiment  44.    By  holding  your  finger  or  a  pencil  in  line 

with  writing  on  the  blackboard,  you  find  that  you  cannot 

see  both  finger  and  blackboard 
distinctly  at  the  same  time  — 
first  one  and  then  the  other 
is  distinct. 

Accommodation.  —  In  order 

FIG.  172.  -Change  of  lens  in  accom-    tQ    foCUS    the    light    Upon    the 
modation.    (Jegi.) 

retina,  the  lens   must  change 
shape  for  every  change  in  the  distance  of  the  object  looked  at 


rays  may  be  bent 


254 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


(see  Fig.  172).  The  shape  of  the  lens  can  be  readily 
changed,  for  it  is  elastic  and  has  muscular  fibers  around  its 
edges. 

Experiment  45.  For  a  few  cents  obtain  from  a  jeweler 
a  convex  lens,  or  use  a  strong  pair  of  spectacles  worn  by 
an  old  person.  Hold  the  lens  a  few  feet  from  a  window 
(darken  any  other  windows  near).  A  little  beyond  the  lens 

hold  a  book,  open  at  a  blank 
page  to  catch  the  image.  Have 
some  one  walk  before  the  win- 
dow. 

Defects  in  the  Eye.  —  Some 
eyes  are  too  long,  and  the  lens 
brings  the  rays  to  a  focus  before 
3  they  reach  the  retina.  Such 
eyes  are  nearsighted  (Fig.  173) 
and  require  glasses  that  round 

rays  for  near  objects  (2)  unless    inward    (concave).        Some    eyes 
concave  glasses  are  used  (3). 

are  too  flat,  and  the  rays   are 

not  brought  to  a  focus  soon  enough.  Such  eyes  are  far- 
sighted  and  require  glasses  that  round  outward  (convex). 
See  Fig.  174. 

Care  of  the  Eyes.  —  Because  the  eyes  can  do  a  large 
amount  of  work  without  giving  pain,  they  are  often 
abused.  When  reading  or 
doing  intricate  work,  turn 
the  eyes  from  the  work  oc- 
casionally and  look  at  some 
distant  object;  stop  work 
before  the  eyes  are  tired. 
Twilight  of  early  evening 
has  ruined  many  good  eyes. 
You  should  always  stop  work  before  the  twilight  begins, 


FIG.  174.  —  FARSIGHTED  EYE  (too 
short)  which  needs  convex  lens  .to 
focus  rays  upon  retina. 


THE  SENSES  255 

for  the  light  fades  so  gradually  that  you  will  surely  be 
straining  the  eyes  before  you  know  it.  Do  not  work 
with  the  light  in  front;  the  glare  of  the  light  makes 
objects  appear  dim.  The  light  should  come  from  above, 
and  (for  right-handed  people)  from  the  left.  Do  not 
read  papers  or  books  printed  in  fine  type.  We  should 
not  read  when  convalescing  from  illness;  with  the  head 
bent  down ;  when  the  eyes  are  sore ;  in  jolting  cars. 
Heating  the  eyes  by  a  burner,  or  drying  the  eyeballs 
in  a  dry,  stove-heated  atmosphere,  using  a  light  with- 
out a  shade,  cause  trouble  with  students'  eyes.  Of 
what  are  blood-shot  eyes  often  a  sign  ?  The  nutrition 
of  the  eye  and  the  optic  nerve  is  not  so  perfect  in  a 
person  whose  organs  of  digestion,  respiration,  and  circu- 
lation have  been  injured  by  alcohol. 

THOUGHT  QUESTIONS.  —  The  Eye.    1.  The  eye  is  shielded  from 

blows  by  bony  projections  of , ,  and .     2.    The  hairs  of 

the  eyebrows  lie  inclined  towards ,  in  order  to  turn from  the 

.     3.   I  find  by  trying  it  that  I  (can  or  cannot  ?)  see  the  position 

of  a  window  with  my  eyes  closed.     4.   The  pupil  appears  to  be  black, 

because  no is from  the  interior  wall  of  the  eye.     I  know  that 

the  iris  is  partly  muscle,  because  it  the  size  of  the .    5.   By 

holding  my  finger  in  line  with  writing  on  the  blackboard,  I  find  that  I 
(can  or  cannot  ?)  see  both  finger  and  writing  distinctly  at  one  time. 

THE   EAR  AND   HEARING 

Sound.  —  Anything  that  is  sending  off  sound  does  so 
by  vibrating,  or  shaking  to  and  fro,  very  rapidly.  For 
instance,  a  vibrating  violin  string  sets  every  particle  of 
air  near  it  swinging  to  and  fro.  The  near  particles 
strike  the  next  ones  and  bounce  back,  these  in  turn 
strike  against  others,  and  thus  vibrations  called  sound 
waves  are  sent  through  space  in  all  directions  from 
the  sounding  body.  We  feel  these  waves  with  the  ear. 


256 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


The  ear  consists  of  three  portions,  the  external  ear, 
the  middle  ear  (or  drum),  and  the  internal  ear  (or  laby- 
rinth, see  Fig.  175).  The  cranial  nerve  connecting 
the  ear  with  the  brain  is  called  the  auditory  nerve. 
This  nerve  goes  no  farther  than  the  internal  ear;  the 
outer  and  middle  ear  pass  on  the  vibrations  of  air  to  the 
ends  of  the  nerve  fibers  in  the  internal  ear. 

The  external  ear  consists  of  a  large  wrinkled  carti- 
lage on  the  exterior  of  the  head  and  a  canal  leading 


The  Hammer 

(Malleus). 


The .  Loops 

(Semicircular 
Canals). 


The  Anvil 
(Incus). 


The  Stirrup 
(Stapes). 


Eustacbian  Tube 
FIG.  175.  — INTERNAL  EAR  (greatly  enlarged). 

from  it,  called  the  meatus.  This  passage  is  closed  at 
its  inner  end  by  the  drum  membrane  or  drum  skin.  It 
is  often  called  the  drum,  but  this  name  is  properly 
applied  to  the  whole  middle  ear.  If  you  look  into  the 
human  ear,  you  cannot  see  the  drum  skin,  even  with  the 
aid  of  a  bright  light,  for  the  passage  is  slightly  curved, 
as  can  be  seen  in  Figure  175.  Hence  a  missile  or  a  fly- 
ing insect  cannot  go  straight  against  the  ear  drum.  The 
skin  lining  this  passage  contains  wax  glands,  which  secrete 


THE  SENSES  2$? 

a  bitter  sticky  wax,  which  helps  to  keep  the  passage  flexible. 
This  wax  catches  dust  and  usually  stops  insects  that  may 
enter.  If  an  insect  enters  the  ear,  it  may  often  be  coaxed 
out  by  a  bright  light  held  close  to  the  ear.  The  ear  wax 
in  a  healthy  ear  dries  with  dust  and  scales  of  epidermis 
and  falls  out  in  flakes,  thus  cleansing  the  ear.  It  is  unwise 
to  probe  into  the  ear  with  a  hard  object  or  even  with  the 
corner  of  a  towel.  It  is  not  necessary  to  insert  the  finger  in 
the  meatus  to  cleanse  it ;  it  is  one  inch  long,  but  only  about 
one  fourth  inch  across.  (How  large  is  the  little  finger?) 
Such  meddling  may  do  harm.  One  of  the  cJdef  advantages  of 
the  study  of  physiology  is  to  warn  us  against  ignorant  med- 
dling with  the  body,  whether  by  stimulating  it,  drugging  it, 
deforming  it,  overheating  it,  half  smothering  it  in  close 
rooms,  living  contrary  to  our  instincts,  etc.  A  bean  or 
pea  is  sometimes  pushed  into  the  ear  by  a  thoughtless 
child.  Pouring  water  into  the  ear  will  only  cause  the 
bean  to  swell.  If  the  ear  wax  is  deposited  too  fast,  it 
will  cause  temporary  deafness  and  earache.  It  may  be 
syringed  out  with  warm  water.  There  should  be  no  haste 
in  removing  a  small  object  from  the  ear  of  a  child  unless 
a  physician  is  present,  as  the  harm  is  usually  done  by  the 
attempts  to  remove  it  and  not  by  the  object.  The  carti- 
laginous ears  on  the  sides  of  the  head  should  be  carefully 
washed  because  of  their  many  crevices.  Each  ear  has 
three  muscles  for  moving  it  (see  Plate  III,  Chart  of  the 
Muscles),  but  they  have  become  »o  weakened  by  disuse 
as  to  be  useless  to  most  people. 

The  middle  ear,  or  drum  chamber,  contains  air  (Fig. 
175).  It  is  separated  from  the  outer  ear  by  the  drum 
membrane.  It  contains  three  bones  (Fig.  175)  which 
stretch  across  it  and  conduct  the  sound  waves  from  the 
drum  membrane  to  the  inner  ear.  The  handle  of  the  first 
s 


2$8  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

bone,  or  hammer,  is  attached  to  the  middle  of  the  drum 
skin  so  as  to  be  affected  by  the  slightest  quiver  of  the 
membrane.  Its  club-shaped  large  end  rests  upon  the  sec- 
ond bone,  or  anvil.  A  prong  from  the  anvil  presses  upon 
the  top  of  the  stirrup,  or  third  bone,  which  really  has  the 
exact  form  of  a  stirrup.  The  base  of  the  stirrup  presses 
upon  the  skin-covered  oval  window,  which  is  in  the  wall 
of  the  inner  ear.  The  middle  ear  is  connected  with  the 
pharynx  by  a  tube  (the  Eustachian  tube  ;  pronounced  yoo- 
stake'e-an,  see  Fig.  175).  This  tube  is  opened  every  time 
we  swallow.  It  allows  the  air  from  the  throat  to  enter  the 
middle  ear  and  keep  the  air  pressure  equal  on  each  side 
of  the  drum  skin.  This  tube  and  the  middle  ear  are  lined 
with  mucous  membrane. 

A  cold  in  the  head  or  a  sore  throat  may  extend  through 
this  tube  to  the  middle  ear  and  affect  the  hearing.  This 
occurs  because  the  tube  is  closed  by  congestion  of  its  lin- 
ing; the  air  of  the  middle  ear  may  be  partly  absorbed, 
and  the  pressure  of  the  outside  air  may  cause  the  drum 
membrane  to  bulge  inward,  and  to  be  stretched  so  tight 
that  it  cannot  vibrate  freely.  Can  you  state  the  connec- 
tions of  the  ear  bones  with  each  other  and  with  the  walls 
of  the  drum  chamber  ? 

Experiments.  —  46.  Close  the  mouth  and  close  the 
nostrils  by  pinching,  and  then  swallow.  This  removes  a 
little  air  from  the  pharynx,  and  the  drum  membrane 
is  pushed  in,  causing  a  slight  crackling  sound.  47-  Close 
the  ears  by  pressing  the  palms  against  them.  Can  you 
hear  anything?  Is  this  effect  the  same  when  the  ears 
are  closed  by  pressing  folded  handkerchiefs  against 
them  ? 

The  inner  ear  is  called  the  labyrinth,  because  of  its 
winding  passages.  There  is  a  spiral  passage  called  the 


THE  SENSES  2  59 

snail  shell  and  three  simpler  passages  called  the  loops  (Fig. 
175).  The  inner  ear  is  filled  with  a  limpid  liquid,  and 
when  the  stirrup  vibrates  against  the  oval  window  the 
liquid  is  shaken.  This  liquid  conveys  the  vibrations  to 
the  ends  of  the  auditory  nerve  found  in  the  snail  shell. 
Thus  the  sound  waves  reach  the  real  end  organs  of  hear- 
ing. There  are  six  thousand  rods  connected  with  the 
ends  of  the  fibers  of  the  auditory  nerve.  It  is  believed 
that  sounds  of  different  pitch  set  different  rods  to  vibrat- 
ing. Thus  the  ear  may  be  said  to  contain  a  wonderful 
harp  of  six  thousand  strings  to  aid  us  in  perceiving  sounds 
of  every  pitch.  Sound  waves  can  also  reach  the  laby- 
rinth through  the  bones  of  the  head. 

Experiment  48.  Hold  a  watch  between  the  lips  and 
notice  its  ticking.  Close  the  teeth  down  upon  it  and 
notice  any  change  in  the  sound.  Cover  one,  then  both, 
ears,  and  note  the  result. 

Sense  of  Equilibrium.  —  Some  fibers  of  the  auditory 
nerve  end  in  the  loops  and  are  not  believed  to  be  used  in 
hearing.  It  is  believed  that  each  loop  acts  like  a  carpen- 
ter's level,  and  the  varying  pressure  of  the  fluid  upon  the 
nerves  in  the  loops  tells  us  the  position  of  the  body  and 
constitutes  the  sense  of  equilibrium. 

Experiment  49.  If  the  body  is  whirled  around  for  a 
little  while,  the  unaccustomed  pressure  of  the  fluid  on  the 
loops  confuses  the  sense  of  equilibrium,  and  dizziness 
results. 

How  do  we  know  the  direction  from  which  sound  comes  ? 
The  external  projections  that  we  call  ears  are  of  little  im- 
portance in  hearing ;  yet  they  enable  us  to  hear  sounds  a 
little  better  from  the  front  than  from  behind.  A  sound 
coming  to  tJie  ears  from  the  side  is  louder  to  the  ear  on  that 
side.  This  enables  us  to  judge  the  direction  of  its  source. 


260  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

Experiment  50.  Let  the  class  stand  in  a  circle.  Blindfold 
some  one  and  place  him  in  the  middle  of  the  circle.  Pass 
a  bell  around  the  circle  and  let  it  be  tapped  at  intervals. 
Can  the  blindfolded  one  point  in  the  direction  whence  the 
sound  comes  ?  Why  does  he  confuse  the  direction  of 
sounds  coming  directly  from  the  front  and  rear? 

Impaired  hearing  and  deafness  may  be  caused  by  dis- 
ease of  the  auditory  nerve,  labyrinth,  middle  ear,  rupture 
of  drum  head,  stoppage  of  the  passage  of  the  outer  ear, 
or  by  inflammation  of  the  lining  of  the  Eustachian  tube.  If 
either  the  auditory  nerve  or  labyrinth  is  diseased,  the  deaf- 
ness may  be  incurable.  Earaches  are  caused  by  sores  or 
inflammation  of  the  outer  or  middle  ear.  They  may  some- 
times be  relieved  by  applying  to  the  ear,  cloths  wrung  out  of 
very  hot  water.  Water  sometimes  gets  into  the  ear  while 
bathing.  It  may  be  removed  by  shaking  the  head  while 
it  is  held  to  one  side.  Putting  cotton  into  the  ears,  or 
wearing  mufflers  over  them,  or  wearing  the  hair  combed 
over  them,  makes  the  ears  tender  by  overheating  them. 
Inflammation  or  sores  sometimes  make  holes  through  the 
drum  membrane  and  impair  the  hearing.  The  hair  around 
the  ears  should  not  be  left  wet.  Scarlet  fever,  mumps, 
catarrh,  a  clap  with  the  hand  upon  the  ear,  quinine  and 
other  drugs,  may  cause  impared  hearing  or  deafness.  To 
cure  a  catarrh  often  restores  the  hearing.1  Pupils  with 
weak  hearing  should  be  given  front  seats.  Dullness  and 
inattention  in  school  are  often  to  be  accounted  for  by 
partial  deafness. 

1  Catarrh  is  often  caused  by  overeating.  A  certain  actor  with  catarrh  went 
to  a  noted  New  York  physician  who  said  :  "  I  can  do  nothing  for  you.  You 
need  a  new  mucous  membrane  for  your  nose.  I  cannot  make  mucous  mem- 
branes." Yet  in  two  years  the  actor  was  well :  for  he  learned  to  eat  moder- 
ately and  ate  simple,  nourishing  foods  (chiefly  raisins,  nuts,  fresh  fruit,  dried 
figs,  and  dates)  and  his  cells  made  him  a  new  mucous  membrane. 


THE  SENSES  26 1 

Experiment  51.  Blindfold  one  of  the  class;  cover  one 
ear  and  hold  a  ticking  watch  near  the  other  ear.  Carry  it 
away  slowly,  and  find  out  how  far  it  can  be  heard.  Test 
the  other  ear  in  the  same  way,  and  measure  the  distance 
for  each  ear.  Are  the  ears  of  the  pupil  equally  sensitive  ? 

THE  VOICE 

The  voice  is  produced  in  the  larynx,  a  cartilaginous  box 
at  the  top  of  the  windpipe.  The  larynx  is  felt  in  the  neck 
as  the  Adam's  apple.  During  the  act  of  swallowing,  it  is 
closed  by  a  trap  door  of  cartilage,  called  the  epiglottis.  It 
is  lined  with  mucous  membrane.  This  lining  is  folded  in 
from  each  side  so  that  the  folds  nearly  meet  in  the  middle. 
The  narrow  slit  between  the  folds  is  called  the  glottis. 
The  liplike  folds  are  inap- 
propriately called  the  vocal 
cJiords.  The  folds  enclose 
many  fibers  of  elastic  tissue ; 
thus  the  vocal  chords  consist 
of  mucous  membrane  and  elas- 
tic tissue.  Usually,  the  breath 
passes  the  vocal  chords  with- 
out setting  them  in  vibration 
(Fig.  176).  By  the  muscles  of 
the  larynx  moving  the  cartilages 
forming  the  larynx,  the  vocal  FIG.  176.- THE  VOCAL  CHORDS  and 

J  the  cartilages  to  which   they  are 

Chords  are   Stretched  tight  and         attached.     Mucous  membrane  re- 

their  edges  brought  close  to- 
gether ;   then  the  breath  cannot  be  sent  out  without  pro- 
ducing sounds  called  the  voice. 

Pitch  and  Loudness  of  Voice.  —  The  more  forcibly  the 
breath  is  sent  out,  the  stronger  the  vibrations  of  the  cJiord 
and  the  louder  the  voice.  The  tighter  the  chords  are 


262  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

stretched,  the  faster  they  vibrate,  the  shriller  the  voice,  just 
as  the  tighter  the  strings  of  a  violin  are  stretched,  the 
higher  the  note.  The  heavier  strings  on  the  violin  pro- 
duce the  lower  notes.  If  the  vocal  chords  are  heavy  with 
blood,  as  during  a  cold,  a  hoarse,  low  voice  results.  The 
longer  strings  on  a  harp  produce  the  lower  notes.  When 
a  boy  reaches  about  sixteen  years  of  age,  the  larynx  en- 
larges, the  vocal  chords  lengthen,  and  his  voice  changes  and 
becomes  lower  in  pitch.  Because  of  the  greater  length 
of  chords,  the  voice  of  a  man  is  about  an  octave  lower  than 
the  voice  of  a  woman. 

Quality  of  Voice.  —  Another  important  property  of  the 
voice  is  quality.  This  depends  upon  the  shape  of  the  cavi- 
ties of  the  throat,  nose,  and  mouth.  Two  persons  may  sing 
or  speak  in  the  same  key  and  with  the  same  loudness,  but 
the  voices  are  not  alike,  for  the  echoing  chambers  just 
named  give  the  two  voices  different  quality.  The  loss  of 
only  one  tooth  may  affect  the  quality  of  the  voice. 

Experiment  52.  Let  a  pupil  go  to  the  back  of  the  room 
and  read  a  paragraph,  and  hold  his  nose  until  partly  through 
the  reading.  Or  the  teacher  may  read  with  his  face  and  hand 
hidden  by  a  large  book.  Let  the  pupils  raise  their  hands 
when  they  notice  a  change  in  the  quality  of  the  reader's 
voice.  Does  the  experiment  show  that  a  "nasal"  tone 
comes  partly  through  the  nose  or  through  the  mouth  only  ? 

Care  of  the  Voice.  —  The  delicate  mucous  membrane  of 
the  air  passages  is  irritated  and  inflamed  by  smoke,  dust, 
alcoholic  drinks,  condiments,  or  exposure.  Sir  Morell 
Mackensie,  M.D.,  says:  "The  hoarse  tones  of  the  chronic 
drinker  are  due  to  chronic  inflammation  of  the  mucous  lining 
of  the  larynx.  The  originally  smooth  surface  being  rough- 
ened and  thickened  by  the  irritation  of  alcohol,  the  vocal 
chords  have  less  freedom  of  movement,  and  their  vibrations 


THE  SENSES  263 

are  muffled  by  the  unevenness  of  their  edges."  Good  habits 
of  breathing  are  the  best  foundation  for  a  good  voice. 
One  must  breathe  naturally  and  hold  the  head  erect  in 
order  to  have  good  control  of  the  voice.  Singing  is  one 
of  the  best  means  of  cultivating  the  voice.  One  should 
not  sing  when  suffering  from  a  cold,  nor  so  long  as  to  tire 
the  vocal  chords.  A  youth  should  not  sing  during  the  years 
when  the  voice  is  changing.  Attempting  to  sing  notes  of 
a  pitch  hardly  within  the  range  of  the  voice  may  strain 
the  vocal  chords. 

REVIEW  QUESTIONS.  —Chapter  VIII.  1.  Describe  an  act  requiring 
the  harmonious  action  of  a  number  of  organs.  2.  Show  that  we  need 
nerve  centers  as  well  as  nerves.  3.  What  is  the  unit  of  nerve  structure? 
4.  Name  the  parts  of  a  neuron.  5.  What  are  nerve  fibers ;  dendrites  ; 
axons  ;  nerves?  6.  What  are  the  parts  of  a  gray  fiber?  Which  parts 
are  lacking  in  a  white  fiber?  What  is  white  matter;  gray  matter? 
7.  Into  what  two  classes  according  to  function  are  cells  and  fibers 
divided?  8.  What  is  a  ganglion ;  a  nerve  center?  9.  Describe  the 
structure  and  work  of  the  spinal  cord.  10.  Trace  the  nerve  impulse 
in  a  reflex  act  from  the  skin  to  the  muscle.  11.  How  are  reflex  acts 
related  to  consciousness  and  the  will?  12.  What  is  the  effect  of 
removing  the  brain  from  lower  animals?  13.  What  are  the  three 
chief  parts  of  the  brain?  14.  Where  is  the  medulla?  What  centers 
are  located  in  it?  15.  How  does  the  condition  of  the  blood  regulate 
the  breathing?  16.  Describe  the  structure  and  function  of  the  cere- 
bellum. 17.  Describe  the  structure  of  the  cerebrum.  18.  How 
many  pairs  of  spinal  nerves ;  cranial  nerves  ?  19.  What  are  the 
functions  of  the  cerebrum?  20.  Locate  several  cerebral  sensory 
centers;  motor  centers.  21.  To  what  extent  does  the  cerebrum  con- 
trol the  lower  nerve  centers?  Why  is  it  well  that  this  control  has  a 
limit?  22.  When  does  the  sympathetic  system  send  messages  to  the 
cerebrum?  23.  Through  what  do  the  sympathetic  fibers  pass  after 
leaving  the  spinal  cord?  24.  What  is  a  plexus?  25.  Why  is  the 
sympathetic  system  so  named?  26.  State  five  differences  between 
the  sympathetic  and  cerebro-spinal  nerves.  Do  the  two  kinds  of 
nerves  form  twc  distinct  systems?  27.  Show  how  the  sympathetic 
nerves  control  the  digestion  of  food;  the  size  of  the  blood  vessels; 
the  heat  of  the  body  28.  Show  how  the  mind  and  viscera  some- 
times affect  each  other. 


264  LESSONS  IN  HYGIENIC  PHYSIOLOGY 

1.  What  supplies  energy  to  the  nervous  system?  2.  Compare  the 
state  of  the  body  during  sleep  and  waking  hours.  3.  Repeat  the  sug- 
gestions concerning  sleep.  4.  What  is  the  best  way  to  prepare  for  a 
severe  mental  effort?  5.  Why  does  change  of  occupation  rest  us? 
Will  it  always  rest  us  ?  6.  Upon  what  fact  does  the  formation  of  habits 
depend?  7.  What  changes  take  place  in  the  nerve  cells  as  an  old  habit 
is  broken?  What  habits  are  hardest  to  break?  8.  Show  the  impor- 
tance of  forming  good  habits.  9.  Distinguish  between  healthy  fatigue 
and  fatigue  caused  by  sluggish  habits.  10.  What  is  the  general  mean- 
ing of  pain?  What  are  four  causes  of  pain?  11.  Discuss  headaches 
resulting  from  excessive  blood  pressure  ;  imperfect  nutrition  ;  from  poi- 
sons and  impure  blood.  12.  How  do  headaches  often  turn  out  to  be  a 
source  of  injury  instead  of  a  benefit?  What  may  be  done  with  benefit 
at  the  first  sign  of  a  sick  headache?  13.  Through  what  system  do 
drugs  generally  act  upon  the  body?  14.  What  are  the  signs  of  ner- 
vousness? What  are  the  causes  of  nervousness  among  city  children? 
15.  How  does  indoor  life  and  the  study  of  books  sometimes  prevent 
sound  development  of  children?  16.  Name  six  ways  in  which  the 
health  of  school  children  may  be  cared  for. 

REVIEW  QUESTIONS.  —  Chapter  IX.  1.  What  sense  should  be 
numbered  with  the  special  senses?  2.  State  several  differences  be- 
tween special  and  general  sensation.  3.  Name  six  general  sensations. 
What  kind  of  general  sensation  can  be  brought  by  any  nerve  ?  4.  Give 
a  reason  for  heeding  each  of  these  general  sensations  :  pain  ;  sleepiness  ; 
thirst ;  hunger ;  fatigue.  State  ways  in  which  each  are  disregarded. 
5.  Describe  the  end  organs  of  the  sense  of  touch.  6.  To  what  two 
things  does  the  expression  "delicacy  of  touch"  refer?  7.  Where  can 
we  tell  the  point  touched  with  the  greatest  exactness  ?  8.  Give  facts 
to  show  that  the  temperature  sense  is  easily  fatigued.  9.  What  parts 
of  the  skin  are  especially  sensitive  to  heat?  10.  What  two  kinds  of 
nerves  give  us  the  muscular  sense?  11.  Which  sense  keeps  us  con- 
scious of  the  position  of  the  limbs?  12.  What  are  the  three  kinds  of 
papillae  in  the  tongue?  Which  kinds  give  us  the  sensation  of  taste? 
13.  What  are  the  three  principal  tastes  ?  14.  Where  do  the  fibers  of 
the  nerves  of  smell  end?  Do  we  smell  solids,  liquids,  or  gases? 
15.  What  are  flavors?  16.  What  is  said  of  the  value  of  taste  and 
smell  as  guides?  17.  What  is  a  common  cause  of  the  sense  of  smell 
becoming  weakened?  Why  do  some  cooks  put  strong  seasoning  in 
food?  18.  State  several  evils  of  high  seasoning  in  food.  19.  State 
the  various  ways  of  entrapping  the  sense  of  taste  in  order  to  use  the 
different  narcotics.  What  is  the  effect  of  narcotics  upon  the  senses  of 
smell  and  taste?  20.  What  is  the  connection  between  pleasant  taste 
and  digestion? 


THE  SENSES  26$ 

1.  Through  what  substance  does  light  travel  to  the  eye?  2.  What 
is  the  orbit,  and  how  is  the  eye  placed  in  it?  3.  Why  do  some  people 
appear  to  have  large  eyes  ?  What  enables  the  eye  to  change  expres- 
sion? 4.  State  the  uses  of  the  eyelids,  lashes,  and  brows.  5.  How 
are  the  tears  formed  and  conducted  away?  What  is  their  use?  6.  De- 
scribe the  three  coats  in  the  wall  of  the  eyeball  and  the  three  parts  of 
its  contents.  7.  What  is  the  use  of  the  muscles  of  the  eye? 

1.  What  are  the  three  divisions  of  the  ear?  2.  Name  the  parts  of 
the  external  ear.  How  is  it  taken  care  of?  3.  Describe  the  middle 
ear  and  the  three  ear  bones.  What  is  the  use  of  the  Eustachian  tube  ? 
4.  Describe  the  inner  ear.  5.  What  gives  the  sense  of  equilibrium? 
6.  How  do  we  know  the  direction  from  which  sound  comes?  7.  What 
are  the  causes  of  impaired  hearing?  8.  What  is  the  larynx ;  epiglottis ; 
vocal  chords;  glottis?  9.  What  causes  the  voice  to  vary  in  loudness; 
pitch  ;  quality?  10.  What  is  stated  concerning  the  care  of  the  voice? 

GENERAL  REVIEW  (Questions  from  State  Examinations).  —  What 
and  where  are  these :  portal  vein;  diaphragm;  vertebra;  aorta?  Name 
five  glands;  five  secretions;  five  tissues.  State  functions  of  each. 
What  arteries  carry  venous  blood?  What  membrane  is  chiefly  affected 
in  catarrh;  peritonitis  (Fig.  134);  pleurisy;  bronchitis?  How  does 
alcohol  cause  the  face  to  flush?  Draw  a  diagram  of  the  alimentary 
canal  (Fig.  120),  writing  the  names  of  these  parts  in  their  proper 
places :  esophagus ;  stomach  ;  pylorus ;  duodenum ;  colon ;  rectum. 
Of  what  tissue  do  each  of  these  consist :  outside  of  stomach  (Fig.  73)  ; 
inside  of  stomach  ;  mass  of  tongue  ;  tendons  ?  What  is  the  function  of: 
aorta;  lacteals;  portal  vein;  ligament?  By  what  system  is  the  body 
put  into  relation  with  the  outside  world ;  its  nutriment  prepared ; 
distributed?  How  is  heat  generated  in  the  body?  How  does  alcohol 
injure  the  lungs?  Name  the  processes  by  which  food  is  converted  into 
tissues  by  the  body  (p.  1 50) .  How  can  you  show  that  the  breath  con- 
tains water;  carbon  dioxid  gas?  (p.  113.)  Bile  is  secreted  from  what, 
by  what,  and  for  what  purposes?  State  three  losses  that  the  body 
is  constantly  sustaining.  Mention  the  subdivisions  of  the  brain  and 
describe  each  as  to  (i)  size;  (2)  form;  (3)  matter;  (4)  position; 
(5)  function.  Suppose  a  blood  cell  in  the  inferior  vena  cava;  trace  its 
route  into  the  aorta.  State  what  you  have  observed  of  the  effects  of 
alcohol  upon  a  healthy  body.  When,  if  ever,  should  alcohol  be  used  ? 
(p.  220.)  Locate  the  appendix  (Fig.  133).  Distinguish  between 
organic  and  inorganic  foods,  and  give  examples.  What  means  has 
the  body  for  combating  disease  germs  ?  State  the  effects  of  muscular 
exercise  upon  six  of  the  principal  organs.  Draw  a  diagram  showing  the 
correct  way  of  ventilating  a  room  heated  by  a  stove  (Fig.  105).  State 
the  effects  of  hasty  eating. 


266 


LESSONS  IN  HYGIENIC  PHYSIOLOGY 


NOTE  ON  INJURIES.  —  For  treatment  of  dislocations,  see  page  60; 
fainting,  see  page  86 ;  cut  blood  vessels,  page  92 ;  for  asphyxia  and 
other  accidents,  see  Figs.  177  to  182. 


FIG.  177.  —  RESUSCITATION,  Inspiration,  by  drawing  the  arms  over  the  head. 


^V^^^B^BVM 

FlG.  178.  —  RESUSCITATION,  Expiraticn,  by  pressing  arms  on  sides  and  chest. 


FIG.  179.  — A  BROKEN  SHIN.  To  keep  bone  from  cutting  flesh  and  skin,  never 
move  the  person  until  a  temporary  splint  has  been  provided  by  tying  walking 
canes  or  umbrellas  around  the  limb  with  handkerchiefs. 


Artery- 


FIG.  180.— SLING  for 
broken  arm. 


FIG.  181.— KNOT  TWISTED 
ON  ARTERY  above  the  cut. 


FIG.  182.— TOE  DISTORTED 
BY  TIGHT  SHOE. 


POISONOUS  SNAKE  BITES  ; 
(The  Macmillan  Co.) 


See  Bailey  and  Coleman's  Biology,  Part  II.,  page  145. 


ACCIDENTS  AND  INFECTION  267 

NOTES  ON  SANITATION.  —  For  detailed  discussion  of  bacteria  and  trans- 
missible diseases  see  Chapter  VI,  pages  122-132. 

NAME  FROM  EXPOSURE  TILL  PATIENT  is  INFECTIOUS 

oi    DISKASE  FIRST  SYMPTOMS  TO  OTHERS 

Diphtheria  2  days  14  days  after  membrane  disappears. 

Mumps  10-22  days  14  days  from  commencement. 

Scarlet  fever  4  days  Until  all  scaling  has  ceased. 

Small  pox  12-17  days  Until  all  scabs  have  fallen,    [cough  cease. 

Measles  14  days  3  days  before  eruption  till  scaling  and 

Typhoid  fever  n  days  Until  diarrhoea  ceases.       [ning  to  whoop. 

Whooping  cough  14  days  3  weeks  before  until  3  weeks  after  begin- 

Typhoid  fever:     How  spread,  see  p.  127;   disposal  of  excrement,  see  p.  132. 

Consumption:  Disposal  of  sputum,  page  132;  frequent  recovery  from,  see 
page  125 ;  spread  by  kissing,  by  drinking  cups,  by  milk  or  meat  from  tuberculous 
animals,  by  droplets  of  spray  during  coughing  or  talking,  and,  rarely,  by  d,ust. 
The  germs  usually  enter  the  body  through  wall  of  intestine,  go  through  lymphatic 
and  circulatory  systems  and  lodge  in  capillaries  of  lungs.  To  prevent  invalid  rein- 
fecting  himself  (in  new  spots)  he  should  carefully  cleanse  his  teeth,  mouth,  and 
throat  with  solution  of  formal  or  lysol  before  eating.  Treatment:  rest,  fresh  and 
cool  air,  sunshine,  abundant  digestible  food.  Place  no  reliance  whatever  on  drugs. 
If  patient  is  not  placed  in  tent  or  on  veranda,  every  window  and  door  should  be 
open  night  and  day. 

Malarial  fever:  Transmitted,  not  by  a  vegetable  germ  (bacterium),  but  by  an 
animalcule  (page  130),  sometimes  parasitic  in  the  anopheles  mosquito.  It  holds  rear 
end  of  body  elevated  at  an  angle  when  still ;  has  four  long  appendages  at  mouth 
(common  mosquito  has  only  three).  It  does  not  fly  before  dusk.  Hence  wire 
screens  to  house  and  mosquito  netting  to  bed  if  rightly  made  and  properly  used 
are  protective.  A  better  way  is  to  leave  no  breeding  places,  —  water  in  tubs,  cans, 
etc. ;  pour  one  ounce  of  kerosene  for  every  15  feet  square  of  standing  water,  or 
stock  all  ponds  and  stagnant  streams  with  fish  to  destroy  wrigglers.  To  cause  ma- 
laria there  must  be  (i)  female  anopheles  mosquito,  (2)  parasites  in  the  insect, 
(3)  a  person  of  unsound  body  and  low  vital  resistance.  Yellow  fever  is  caused  by 
the  bite  of  an  infected  stegomyia  mosquito.  See  Howard's  Mosquitoes  (McClure, 
N.Y.,  1901).  The  discovery  has  made  the  disease  subject  to  control. 

Tetanus  (lockjaw)  :  Germs  are  killed  by  exposure  to  air  and  light.  Hence 
the  disease  arises  from  deep  ragged  wounds  bound  up  without  disinfection. 

The  chief  Disinfectants  are :  fresh  air,  sunshine,  heat,  formaldehyde,  etc. 
Airing  and  sunning  will  destroy  germs  in  bedding  and  clothing  as  effectually  as 
chemicals.  Boiling  and  steaming  are  the  best  ways  of  applying  heat.  Formal- 
dehyde is  a  gas.  After  room  is  sealed  and  strips  of  paper  pasted  all  over  cracks,  a 
specially  constructed  generator  is  applied  to  keyhole,  and  room  kept  closed  for  12 
hours.  Mercuric  chloride  (corrosive  sublimate)  is  used  one  part  to  loco  parts  of 
water  for  disinfecting  soiled  clothing,  towels,  and  utensils.  In  place  of  this,  Car- 
bolic acid,  5  per  cent  solution,  may  be  used,  but  it  is  not  so  good  a  germicide. 

Milk  may  be  sterilized  by  boiling,  but  boiled  milk  is  not  digestible  nor  nutri- 
tious. Milk  may  be  pasteurized  by  immersing  bottles  of  milk  in  water  which  is 
kept  nearly  (but  not  quite)  at  boiling  point  (i6o°F.)  for  five  minutes.  But  this 
makes  the  milk  less  valuable  than  fresh  milk  and  destroys  beneficent  microbes. 
Butter-milk  has  many  such  microbes  which  kill  injurious  microbes  and  purify  the 
stomach.  Cleanliness,  or  an  aseptic  condition,  is  far  preferable  to  antiseptics. 


GLOSSARY 

Abdo'men.    The  largest  cavity  of  the  body,  containing  the  stomach,  kidneys,  etc. 
Absorp'tion.    The  taking  up  of  nutriment  by  the  blood  vessels  or  lymphatics. 
Albu'min.     A  group  of  nourishing  substances  which  contain  nitrogen,  and  resemble 

in  nature  white-of-egg,  or  albumen. 
Anat'omy  (Gr.  anatemnein,  to  cut  up).    The  science  of  the  structure  of  living 

things. 

Antisep'tic.    Any  substance  which  destroys  bacteria  and  prevents  rotting. 
Antitox'in.     A  substance  which  neutralizes  the  toxins  formed  by  bacteria. 
Aor'ta  (Lat.}.    The  great  artery  arising  from  the  left  ventricle  of  the  heart. 
Ar'tery.    A  vessel  which  carries  blood  from  the  heart. 
Au'ricles  (Lat.  auricula,  a  little  ear).     The    chambers  at   the  upper  part  of  the 

heart,  which  receive  blood  from  the  veins. 
Bacillus.     A  rod-shaped  bacterium. 
Bacte'ria.    Vegetable  germs  or  microbes;  most  of  them  feed  by  causing  decay  or 

putrefaction  in  albuminous  substances. 
Bron'chial  tubes.     The  smaller  branches  of  the  windpipe. 
Bronchi'tis.     Inflammation  of  the  bronchial  tubes;  a  "  cold  in  the  chest." 
Cap'illary  (Lat.  capillus,  hair).     The  name  given  to  the  smallest  blood  vessels 

because  of  their  size. 

Carbon  diox'id.     An  inactive  gas  formed  by  the  union  of  carbon  and  oxygen. 
Car'tilage.     Gristle.    An  elastic,  flexible  material  found  at  the  joints. 
Ca'sein  (Lat.  caseus,  cheese).    An   albumen   obtained  from  curd  when  whey  is 

squeezed  out  of  sour  milk. 

Catarrh'.     Inflammation  of  a  mucous  membrane. 
Cell  (Lat.  cell.a,  a  room) .    A  bit  of  protoplasm  containing  a  nucleus. 
Cerebellum.     The  hinder  and  lower  division  of  the  brain. 
Cer'ebro-spinal.     Pertaining  to  the  brain  and  spinal  cord. 
Cer'ebrum  (Lot.}.    The  chief  division  of  the  brain.     The  large  brain. 
Chyle  (Gr.  chulos,  juice).      The  digested  nutritious  part  of  the  food  prepared  in 

and  absorbed  from  the  intestines. 

Chyme.    The  partly  digested  food  which  passes  from  the  stomach  to  the  intestine. 
Cil'ia.     Microscopic  processes  on  cells,  chiefly  of  the  air  passages. 
Coagula'tion.     The  turning  of  blood  from  a  liquid  to  a  semi-solid  state.     Clotting. 
Conges'tion.     An  unhealthy  accumulation  of  blood  in  any  part  of  the  body. 
Connec'tive  tissue.     A  tough,  fibrous  material  used  for  binding  together  the  parts 

of  organs. 

Convolu'tion.     One  of  the  winding  ridges  on  the  surface  of  the  brain. 
Cor'puscle.     The  minute  bodies  which  float  in  the  blood  liquid. 
Degeneration.     A  change  in  the  structure  of  any  organ  which  makes  it  less  fit  to 

perform  its  duty  or  function. 

Den'tine.     The  hard  substance  which  forms  most  of  a  tooth.     Ivory. 
Di'aphragm.      The  muscular    membrane  which    separates    the   chest  from   the 

abdomen. 

268 


GLOSSARY  269 

Diges'tiofl.     The  liquefaction  and  preparation  of  the  nutritious  parts  of  the  food 

for  absorption  from  the  alimentary  canal. 
Dislocation.    The  forcing  of  a  bone  out  of  its  socket. 
Dor'sal.     Pertaining  to  the  back  of  the  body. 
Duct.     A  tube  by  which  fluid  is  conveyed  from  a  gland. 
En'zyme.     An  unorganized  ferment.     See  Ferment. 
Eusta'chian  (from  an  Italian  anatomist  named  Eustachi).     The  tube  which  leads 

from  the  throat  to  the  middle  ear. 
Fer'ment.    An  organized,  microscopic,  vegetable  germ,  as  yeast,  which  turns  sugar 

into  alcohol  and  carbon  dioxid. 
Fi'ber.     A  slender  thread. 

Fi'brin.     The  solid  substance  which  forms  (in  threads)  when  blood  clots. 
Fol'licle.    A  little  cavity,  or  pit. 

Func'tion.     The  special  action,  or  duty,  of  any  organ. 
Gan'glion.     A  group  of  nerve  cells. 

Gas'tric  (Lot. gaster,  stomach).     Belonging  to  the  stomach. 
Gland.     An   organ  which   forms  and  separates  from   the  blood  a  characteristic 

liquid,  either  for  use  in  the  body  (secretion),  or  for  removal  from  it  (excretion). 
Gly'cogen.     Liver  starch,  the  form  in  which  carbo-hydrates  are  stored  in  the  liver 

until  needed. 

Hemoglo'bin.     The  coloring  matter  in  red  blood  cells.    It  is  oxygen-bearing. 
Hem'orrhage.     Vigorous  bleeding. 
Hepat'ic.     Pertaining  to  the  liver. 
Hy'giene.     The  science  of  preserving  health. 

Immu'nity.     Exemption  from  a  disease  because  of  having  its  antitoxin  in  the  blood. 
Inorgan'ic.     Not  organized  into  cells  or  organs.     Lifeless. 
In'stinct.     An  inherited  habit. 

Inver'tebrate.    Term  applied  to  animals  having  no  backbone. 
Lach'rymal  (La/,  lacrima,  a  tear).     Pertaining  to  tears. 

Lac'teals.     The  lymphatics,  or  absorbents,  of  the  small  intestine.     During  diges- 
tion they  are  filled  with  milky-looking  chyle. 
Lig'ament.    A  cord  or  band  binding  bones  together  at  joints. 
Lymph.     A  colorless  liquid  which  exudes  from  the  blood  vessels  and  bathes  the 

tissues  and  organs. 

Lymphat'ic.    A  tube  which  conveys  lymph  from  the  lymph  spaces  to  the  veins. 
Mammal'ia  (Lat.  mamma,  a  breast).    The  name  given  to  the  highest  division  of 

backboned  animals,  because  the  females  suckle  the  young. 
Mea'tus  ( I. at.,  a  going,  or  course) .    A  passage,  or  channel,  as  the  external  auditory 

meatus  which  leads  from  the  outer  to  the  middle  part  of  the  ear. 
Medul'la  oblonga'ta.    The  continuation  of  the  spinal  cord,  or  marrow,  into  the 

skull. 

Mem'brane.    A  thin  sheet  of  tissue. 
Mi'tral.    Another  name  for  the  bicuspid  valve  between  the  left  auricle  and  ventricle 

of  the  heart,  which  has  two  flaps,  like  the  miter  of  a  bishop. 
Mo'tor.     Pertaining  to  movement. 

Mu'cus.     A  viscid  liquid  secreted  by  mucous  membranes. 
Narcot'ic.     Any  substance  which  dulls  or  benumbs  the  nerves,  and  in  larger  doses 

produces  unnatural  sleep. 
Neu'ron.    A  nerve  cell  with  all  its  branches. 
Nu'cleus.    A  spot  in  a  cell  which  controls  its  growth. 


2/0  GLOSSARY 

Olfac'tory  (Lat.  olfacere,  to  smell).     Pertaining  to  the  sense  of  smell. 

Op'tic.     Pertaining  to  the  sense  of  sight. 

Or'gan  (Lat.  organum,  an  instrument  or  tool).    A  portion  of  the  body  having  some 

special  function  or  duty. 

Osmo'sis.     Exchange  of  two  solutions  through  an  organic  membrane. 
Palpita'tion.     A  violent  and  irregular  beating  of  the  heart. 
Pel'vis  (Lat.,  a  basin).     The  bony  ring  made  of  the  sacrum  and  the  two  hip  bones 

which  surrounds  the  lower  part  of  the  abdomen. 
Perios'teum  (Or.  peri,  around;    osteon,  a  bone).     A  fibrous  membrane  which 

surrounds  the  bones. 
Physiol'ogy.     The  science  which  treats  of  the  actions  or  uses  of  the  different  parts 

of  animals  and  plants.     The  science  of  function. 
Pro'toplasm.    A  jelly-like  nitrogenous  substance  in  every  living  cell. 
Pul'monary.     Pertaining  to  the  lungs. 
Re'flex  action.    An  involuntary  movement  produced  by  an  excitation  traveling 

along  a  sensory  nerve  to  a  center,  where  it  is  turned  back,  or  reflected,  along  a 

motor  nerve. 

Re'nal  (Lat.  renes,  the  kidneys).     Pertaining  to  the  kidneys. 
Ret'ina  (Lat.  rete,  a  net).     The  transparent  nervous  membrane  which  lines  the 

eyeball. 
Sa'crum  (Lat.,  sacred).     The  large  bone  near  the  lower  end  of  the  spine,  having 

the  hip  bones  attached  to  its  sides. 

Sclerot'ic  (Gr.  skleros,  hard,  tough).    The  tough  outer  coat  of  the  eyeball. 
Seba'ceous  glands  (Lat.  sebum,  tallow).    The  oil  glands  of  the  skin. 
Secre'tions.     Useful  liquids  prepared  from  the  blood  by  glands. 
Semilu'nar  (Lat.  semi,  half;  luna,  moon).     Shaped  like  a  half  moon. 
Se'rum  (Lat.,  whey).     The  liquid  part  which  separates  from  the  clot  when  blood 

coagulates. 
Stim'ulant  (Lat.  stimulare,  to  goad  or  stir  up).     Any  substance  which  excites 

the  body  to  do  extra  work,  yet  supplies  inconsiderable  or  no  nourishment. 
Tho'rax  (Gr.,  a  breastplate).    The  chest.     The  upper  cavity  of  the  trunk. 
Tis'sue  (Lat.  texere,  to  weave).     The  name  given  to  the  several  materials  found 

in  the  structure  of  the  various  organs. 
Tra'chea  ( Gr.  trachus,  rough) .     The  windpipe, 
Tricus'pid  (Lat.  tri,  three;  cuspis,  a  point).     Having  three  points. 
Tym'panum  (Lat.,  a  drum).     The  middle  or  drum  chamber  of  the  ear. 
U'rea.    A  white  crystalline  solid  secreted  in  solution  in  the  kidneys. 
Ure'ter  (Lat.}.     The  tube  passing  from  the  kidneys  to  the  bladder. 
U'vula.     The  fleshy  tip  of  the  soft  palate. 
Var'icose.     A  chronically  distended  vein. 
Vas'cular.     Possessing  many  vessels  or  tubes. 

Vasomo'tor.     Producing  contraction  or  dilation  in  the  walls  of  vessels. 
Ven'tral  (Lat.  venter,  the  belly).    Pertaining  to  the  front,  or  belly,  side  of  the  body. 
Ven'tricle.     A  small  cavity,  as  the  ventricles  of  the  heart  and  brain. 
Ver'tebra  (Lat.,  from  vertere,  to  turn).    The  name  of  each  of  the  bones  of  the 

spine. 
Vil'lus  (pi.  villi;   Lat.,  shaggy  hair).     The  minute  hair-like  projections  of  the 

mucous  membrane  of  the  small  intestine. 
Vol'untary.     Actions  performed  under  control  of  the  will. 
Yeast.    Single-celled  plants  which  cause  fermentation.     See  Ferment. 


INDEX 


As  set  definitions  have  become  objectionable  to  many  teachers,  the  references  in  this  index 
to  pages  where  the  meanings  of  technical  words  are  explained,  are  printed  in  bold- 
faced type. 


Absorption  of  food,  150. 
Accidents,  266. 
Air,  composition  of,  113. 
Albino,  19. 
Albumin,  143. 

Alcohol,  124,  130,  132,  133,  152,  206, 
and  food,  175. 
and  Germany,  226. 
and  physicians,  180. 
Effect  on 

bones,  48. 

circulation,  100. 

lungs,  119. 

mucous  membrane,  94, 

muscle,  69. 

nerves,  214. 

skin,  27,  30. 

tissues,  14. 
Ameba,  3,  4. 
Anatomy,  8. 
Anemia,  99,  208. 
Antitoxin,  128. 
Aorta,  82. 

Appeiite  as  guide,  145. 
Arm.  36. 
Artery,  81,  92. 
Asphyxia,  266. 
Assimilation,  139,  150. 
Asthma,  118. 
Athletics,  61. 
Auricle,  81. 
Automatic  action,  191. 
Axon,  187. 

Bacillus,  125. 
Backache,  201. 
Bacteria,  123. 


Baths,  28,  29, 131. 
Bile,  162. 
Biliousness,  235. 
Bismarck  and  beer,  226. 
Bleeding,  93. 
246.    Blood,  circuit  of,  81. 

parts  of,  90. 
Boils,  129. 
Bones,  composition  of,  40. 

cranial,  43. 

facial,  43. 

forms,  uses,  39,  45. 

growth  of,  47. 

health  of,  47. 

Latin  names  of,  35. 

structure  of,  39. 
Brain,  10,  190. 

coverings  of,  192. 
Breathing,  102. 

abdominal,  HI. 

chest,  HI. 

full,  H2. 

Calomel,  131,  234. 

Capillary,  84. 

Carbon  dioxid,  15,  105, 113, 124, 141, 

Catarrh,  118,  120,  209,  260. 

Cell,  4,  5,  6. 

air,  104. 

blood,  46,  79,  $o,  128. 

community,  5. 

nerve,  7,  186. 
Cerebellum,  191. 
Cerebrum,  192,  194,  195. 
Chyme,  160. 

Cigarettes,  119,  151,  152,  213. 
Cilia,  105. 
271 


272 


INDEX 


Circulation,  79. 

lymphatic,  93. 

organs  of,  79. 

portal,  91. 

pulmonary,  92. 

renal,  92. 
Climate,  32,  67. 
Clothing,  31,  85,  88,  120,  197. 
Coagulation,  92. 
Coddling,  30,  114,  119. 
Complexion,  20,  89. 
Condiment,  152. 
Consumption,  125,  132,  267. 
Cooking,  176,  179,  246. 
Cranium,  43. 

Deafness,  260. 
Deformities,  48. 
Defective  vision,  254. 
Dendron,  186. 
Dermis,  17. 
Diaphragm,  106. 
Digestion,  138,  149,  155. 
Drawing,  exercises  in,  15,  242. 
Duct,  12. 
Dust,  115. 

Ear,  255. 
Emulsion,  161. 
Energy,  138,  139,  140,  141. 
Enzyme,  155. 
Epidermis,  17,  19. 
Equilibrium,  259. 
Esophagus,  103,  157. 
Excretion,  12. 
Exercise,  67. 
Eye,  248. 

Fainting,  86. 

Fat,  143. 

Fatigue,  60,  201,  202,  206. 

Ferment,  155. 

Fermentation,  132. 

Fiber,  5. 

Flesh,  170. 

Follicle,  20. 

Food,  14,  138,  176. 

composition  of,  147. 

cost  of,  174. 

proportions,  148. 

sources  of,  144. 
Food  stuffs,  141,  167. 
Freckles,  19,  24. 
Fruit,  168. 
Function,  8. 


Ganglion,  188. 
Gastric  juice,  159. 
Gladstone  and  chewing,  159. 

and  exercise,  68. 
Glands,  12. 
Glycogen,  162. 
Grain,  172. 

Gravity  and  blood,  81. 
Gullet,  103,  157. 
Gymnastics,  62. 

Habits,  203. 
Hair,  20. 
Hand,  36. 
Headaches,  207. 
Health,  13. 

care  of,  65. 

common  sense  and,  65. 

modern  life  and,  65. 

of  bones,  47. 

of  circulation,  97. 

of  nerves,  201. 

of  skin,  28. 

school  and,  211. 
Heart,  79,  80. 

breathing  and,  87. 

exercise  and,  86. 

nerves  of,  89. 

nourishment  of,  89. 
Heredity,  63,  167,  212. 
Hygiene,  8. 

Indigestion,  166. 
Indoor  life,  27. 
Inorganic,  8. 
Instinct,  67,  238. 
Intercellular,  13. 
Intestine,  small,  150,  160. 
large,  150,  163. 

Joints,  45. 

kinds  of,  47. 
Kidneys,  92,  col.  fig.  2. 

Labor,  division  of,  7. 

mental  and  physical,  68. 
Labyrinth,  256. 
Lacteal,  95,  161. 
Larynx,  103. 
Ligament,  47. 
Lime,  13,  40. 
Liver,  162. 
Lobule  of  lungs,  104. 

of  liver,  163. 
Lungs,  105. 

capacity  of,  121. 


INDEX 


273 


Lymph,  79,  93,  ia8 

spaces,  93. 

glands,  97. 
Lymphatics,  98. 

Madder,  47. 
Malaria,  131. 
Meatus,  257. 
Membrane,  5. 
Microbe,  124. 
Milk,  141,  171. 
Mithridates,  231. 
Mole,  24. 
Mosquito,  131. 
Motor  nerve,  10,  188. 
Mouth  breathing,  117. 
Muscles  and  health,  62. 

chart  of,  72. 

classified,  55. 

control  of,  58. 

growth  of,  57. 

kinds  of,  5. 

names  of,  57,  71. 

of  skin,  24. 

structure  of,  54. 
Muscular  sense,  242. 

Nails,  21. 

Narcotics  and  stimulants,  14,  27,  48,  69 
Plate  X,  100,  119,  132-135,  151 
152, 175, 176, 179, 180, 209,  212, 214 
Fig.  160,  215,  216,  217-237,  246. 

Natural  living,  27,  28,  30,  64,  67,  in,  120, 
216,  221,  244,  247. 

Nature  of  germ  diseases,  123. 

Nerve,  10,  187. 
cranial,  194. 
spinal,  193. 

Neuron,  186. 

Nicotin,  14,  194. 

Nucleolus,  5. 

Nucleus,  5. 

Nutrition,  137. 

Nuts,  168,  169. 

Oatmeal,  141,  179. 
Oil  glands,  22. 
Opium,  14,  130,  209. 
Orbit,  248. 
Organ,  8. 
Organic,  8. 
Outdoor  life,  27,  30. 
Oxidation,  14,  13.9,  140. 
Oxygen,  14,  ioi,  105,  113. 


Pancreas,  161. 

Papilla,  18,  20. 

Patent  medicines,  134,  232. 

Periosteum,  47. 

Peristalsis,  56. 

Peritoneum,  163. 

Pharynx,  103,  157. 

Physiology,  8. 

Pigment,  19. 

Pimple,  24,  129. 

Plasma,  90. 

Pleura,  105. 

Plexus,  198. 

Poison,  14,  216. 

Portal  vein,  91. 

Posture,  49,  50,  71,  213. 

Proteid,  143. 

Protoplasm,  5. 

Ptomaine,  126. 

Ptyalin,  156. 

Pulse,  82. 

Pylorus,  j6o. 

Quinine,  131. 

Ration,  145. 

Reflex  action,  189. 

Respiration,  102. 

Retina,  251. 

Review,  34,  51,  135,  181,  263. 

Ribs,  42,  108. 

Saliva,  155. 

Savages,  7,  64,  167. 

Scar,  24. 

Secretion,  12. 

Sensation,  general,  238,  239. 

Senses,  238. 

Sensory,  10,  188. 

Serum,  92. 

Shoes,  49,  66,  101. 

Sight,  249. 

Skeleton,  34,  35. 

subdivisions  of,  41. 
Skin,  16. 

care  of,  29. 

structure,  16. 

training  the,  28. 
Skull,  43- 
Sleep.  202. 
Smell,  243,  245. 
Spinal  cord,  188. 
Spine,  41. 

deformed,  49. 
Spleen,  97. 


2/4 

Starch,  142. 
Stomach,  159. 
Strychnin,  14,  130 
Sugar,  142. 
Sunlight,  20. 
Suture,  45. 
Sweat,  23,  26. 
Sweeping,  115. 
Sympathetic  system,  198. 
Synovial  fluid,  47. 

Tanner's  fast,  217. 

Taste,  242,  245. 

Tear  glands,  249. 

Temperature,  25,  26,  138,  241. 

Tendon,  55. 

Thermic  nerves,  25,  241. 

Tissue,  i,  5,  8,  9,  15. 

bony,  13. 

cartilaginous,  12. 

connective,  n. 

epithelial,  12. 

fatty,  n. 

reaster,  9. 

muscular,  9. 

nervous,  9. 

supporting,  9. 


INDEX 


Tobacco,  14,  101,  151,  152,  246. 
Effect  on  heart,  100. 

lungs,  119. 
Touch,  240. 
Toxin,  126. 
Trachea,  103. 
Typhoid  fever,  127,  132. 

Urea,  139,  144. 

Vagus  nerve,  89. 
Valve,  8,  87. 
Vasomotor  nerves,  200. 
Vein,  81,  92. 
Ventilation,  115. 
Ventricle,  81. 
Vermiform  appendix,  163. 
Vertebra,  41. 
Villi,  161. 
Voice,  261. 

Wart,  24. 

Waste  products,  139,  144. 
Wells,  127. 

Writing,  exercises  in,  15,  33,  70, 132, 179, 
237- 

Yeast,  123,  124,  132. 


^Description  of  tye 

N.B.  All  technical  names  are  in  parentheses  to  show  they  are  to  be  omitted 
except  with  the  most  advanced  classes. 

Plan  of  the  Manikin.  Plates  I  and  II  show  the  outside  and  in- 
side surfaces  of  the  front  wall  of  the  trunk  in  their  natural  relation. 
Plate  V  shows  the  inside  of  the  rear  wall  of  the  trunk,  while  Plates  III 
and  IV  show  the  front  and  rear  surfaces  of  the  organs  of  the  trunk  in 
their  true  positions  with  reference  to  each  other,  and  in  their  true  posi- 
tions in  the  trunk. 

Plate  I  shows  the  following  muscles :  shoulder  cap  muscle  (deltoid} 
lifts  whole  arm  ;  the  major  pectoral  (pectoralis  major}  on  chest  draws 
arm  down  and  forward ;  a  small  portion  of  muscle  of  back  (trapezius) 
that  draws  head  and  shoulders  back ;  bowing  muscles  (sterno-mastoid) 
bow  the  head  (one  acting  alone  turns  head)  ;  straight  muscle  of  abdomen 
(rcctits  abiiominis  shown  inclosed  in  its  sheath)  bends  the  body  for- 
ward :  outer  oblique  muscle  (obliquus  externus}  twists  the  body  ;  if  its 
partner  acts  with  it,  they  draw  in  the  abdominal  wall  and  aid  in  sending 
the  breath  out ;  upper  portion  of  muscle  that  swings  leg  out  (yastus  ex- 
ternus}; swings  leg  forward (rectus  femoris};  and  tailors  muscle  (sar- 
turius},  used  in  crossing  the  leg. 

Plate  II.  The  cut  edges  of  abdominal  wall  show  three  layers  of 
muscles.  Front  half  of  diaphragm  is  shown ;  at  the  breast  bone  it 
extends  as  high  as  the  fifth  rib ;  at  the  side  it  extends  to  the  lowest  ribs. 
The  breast  bone  (sternum}  is  shown  to  be  in  two  parts,  which  do  not 
unite  until  late  in  life.  The  inner  layer  of  muscles  between  the  ribs  (in- 
ternal intercostal}  are  shown  to  slant  outward  and  downward.  In  the 
shoulder  are  seen  sections  of  the  collar  bone,  shoulder  blade,  and  upper 
arm  bone. 

Plate  III.  Organs  of  Chest  and  Abdomen,  with  a  strip  of  the  dia- 
phragm between.  Two&MgVj  heart',  aorta;  ascending  and  descending 
vena  cava ;  carotid  arteries  (to  head)  ;  jugular  vein  (to  head)  ;  wind- 
pipe (trachea)  ;  thyroid  gland,  which  manufactures  antitoxins  and  sup- 
plies them  to  the  blood  for  killing  germs.  Touching  the  diaphragm 
below  are :  Liver  on  right  (right  and  left  lobes)  ;  Stomach  on  left ; 
Spleen  to  left  of  stomach.  Numerous  folds  of  the  small  intestine  are 
seen,  the  first  portion  (duodenum}  passes  behind  large  intestine,  or 
colon  (see  Plate  IV)  ;  the  second  portion  (jejunum}  and  third  portion 
(He u in)  being  surrounded  by  the  colon.  The  ascending, transverse,  and 
descending  colon  are  visible;  also  the  S-shaped  bend  (sigmoid  flexure); 
the  straight  part  of  colon  (the  rectum}  is  behind  the  bladder,  hence  it 
shows  on  next  plate.  Which  overlaps  the  other  in  front,  the  stomach 
or  the  liver? 

Plate  IV  shows  rear  view  of  the  same  organs  as  Plate  III.  The 
branching  of  the  windpipe  and  the  connections  between  heart  and  lungs 
are  more  plainly  seen  from  the  rear.  The  pulmonary  veins  (carrying 
pure  blood  to  the  heart) ;  a  small  portion  of  pulmonary  artery  ( just 


above  the  heart)  ;  the  stump  of  the  ascending  vena  cava.  The  rings 
of  cartilage  in  windpipe  are  seen  to  be  incomplete  behind.  The  lower 
portion  of  the  gullet  is  shown  piercing  the  diaphragm.  For  upper 
portion  of  gullet  see  Plate  V.  The  pancreas  lies  behind  the  stomach 
(long,  pinkish).  The  green  bile  duct  is  shown  leading  from  liver  to 
small  intestine.  The  green  gall  bladder,  for  storage  of  bile,  is  shown 
connected  with  bile  duct  by  the  gall  duct.  The  large  artery  in  the 
intestine  is  shown  cut  off  from  the  aorta  of  Plate  V.  The  portal  vein, 
with  its  many  branches  for  bringing  digested  food  from  the  intestines, 
is  shown  leading  upward  to  the  liver.  It  enters  the  liver  just  under 
a  notch  which  is  supposed  to  look  like  a  portal  or  door. 

Plate  V.  Funnel-shaped  pharynx,  opening  into  gullet  (esophagus} 
below.  Large  artery  and  vein  to  arm  are  shown.  Aorta  is  shown  cut 
off  just  after  it  makes  the  great  bend  shown  in  Plate  III.  Ribs  slanting 
downward  from  spine.  Azygos  vein  with  branches  following  each  rib ; 
aorta  sends  branch  along  each  rib.  Ascending  vena  cava  cut  off  from 
heart  in  Plate  IV.  Aorta  branches  below  into  two  large  arteries  (iliac}. 
Muscle  (psoas}  from  spine  to  thigh  bone.  Tubes  (ureters}  from  kid- 
neys to  bladder.  Arteries  and  veins'  (renal}  to  kidneys.  Suprarenal 
capsules,  on  top  of  kidneys  (function  similar  to  thyroid  gland).  Bones, 
sections  of  shoulder  bones,  hip  bones,  and  thigh  bone. 

Plate  VI.  Cerebrum  and  cerebellum  shown  resting  on  floor  of  the 
skull ;  folds  (convolutions}  of  cerebellum  smaller  and  more  regular  than 
those  of  cerebrum.  Upper  portion  of  spinal  cord  (medulla  oblongata}  ; 
optic  nerve ;  eyeball.  Lower  jaw  bone  (inferior  maxillary)  with  outer 
portion  of  lower  and  upper  jaws  removed,  to  show  roots  of  teeth  with  the 
nerves  and  blood  vessels  that  supply  them.  Tongue  bone  (hyoid}  ;  jug- 
ular vein  ;  carotid  artery.  Sympathetic  ganglia  and  nerves  among  mus- 
cular fibers  of  the  neck. 

Plate  VII.  Section  of  brain  shows  layer  of  gray  matter  (cortex)  on 
outside  ;  depth  of  convolutions ;  cerebral  nerve  centers  (optic  thalamus, 
corpus  sir iatum,  pans}  ;  band  of  white  matter  (corpus  callosum}  connect- 
ing the  two  hemispheres.  Medulla-,  fibers  of  olfactory  nerve-,  upper 
part  of  left  nasal  chamber.  Scroll  (turbinated}  bones  which  increase 
surface  of  nasal  passages  for  warming  air  before  it  goes  to  lungs.  Throat 
(pharynx)  with  opening  of  tube  leading  to  ear.  Epiglottis  (raised)  ; 
upper  portions  of  gullet  and  windpipe.  Section  of  skull  and  vertebra ; 
spinal  cord. 

Plate  VIII.  Main  blood  vessels  of  arm,  leg,  head,  and  trunk  ;  circu- 
lation through  lungs  ;  four  chambers  of  heart  and  connections  of  blood 
vessels  with  it.  Circulation  through  spleen  (left  of  stomach)  ;  kidney 
(below  the  liver).  Portal  vein  from  intestines  to  liver  (below  right 
lung).  Hepatic  vein  from  liver  to  ascending  vena  cava.  Thoracic  duct 
(colorless)  leading  from  small  intestine,  passing  back  of  heart  and 
emptying  into  vein  from  left  arm. 

NOTE  TO  TEACHER.  —  Read  this  description  to  the  class  very  slowly,  while 
the  pupils  identify  each  part.  Have  periodical  recitations  on  manikin  and 
have  pupils  refer  to  it  throughout  the  course. 


PLATE      I 


"m 


I 


rvi'w   ' 


PLATE    IV. 

Viscera  (rear  view).  Student  will  find 
ducts  from  the  liver  and  pancreaa 
entering  duodenum  together;  also, 
mesenteric  artery  leading  to  intestine* 
and  portal  vein  leading  from  them  to 
liver. 


PLATE     V 


'J,\ 


F 


^S 


CL 

'.'ii 
1  ' 


BLADO 


&&&. 


PLATE     VI, 


PLATE     VII. 


PLATE     VIII. 


The  pupil  will  trace  the  circulation  of  the  blood  from  the  body  through  the 
right  side  of  the  heart  to  the  lungs  ;  and  from  the  lungs  through  the  leftside 
of  the  heart  to  the  body;  also  trace  the  portal  circulation  from  the  digestive 


XB  65498 


219031 


• 


